Device and method for generating broadcast signal frame by using enhanced layer physical layer pipe corresponding to injection level information

ABSTRACT

An apparatus for generating broadcast signal frame according to an embodiment of the present invention includes a combiner configured to generate a multiplexed signal by combining a core layer signal and an enhanced layer signal; a power normalizer configured to reduce power of the multiplexed signal to a power level corresponding to the core layer signal; a time interleaver configured to generate a time-interleaved signal by performing time-interleaving that is applied to both the core layer signal and the enhanced layer signal; and a frame builder configured to generate a broadcast signal frame including a preamble for signaling start position information and size information for each of Physical Layer Pipes (PLPs). In this case, the Physical Layer Pipes include a core layer physical layer pipe corresponding to the core layer signal and an enhanced layer physical layer pipe corresponding to the enhanced layer signal.

TECHNICAL FIELD

The present invention relates to broadcast signal transmission/receptiontechnology that is used in a broadcasting system and, more particularly,to a broadcast signal transmission/reception system that uses timeinterleaving.

BACKGROUND ART

Bit-Interleaved Coded Modulation (BICM) is bandwidth-efficienttransmission technology, and is implemented in such a manner that anerror-correction coder, a bit-by-bit interleaver and a high-ordermodulator are combined with one another.

BICM can provide excellent performance using a simple structure becauseit uses a low-density parity check (LDPC) coder or a Turbo coder as theerror-correction coder. Furthermore, BICM can provide high-levelflexibility because it can select modulation order and the length andcode rate of an error correction code in various forms. Due to theseadvantages, BICM has been used in broadcasting standards, such as DVB-T2and DVB-NGH, and has a strong possibility of being used in othernext-generation broadcasting systems.

In order to support multiple services simultaneously, multiplexing,which is a process of mixing a plurality of signals, is required. Ofmultiplexing techniques, currently widely used techniques include TimeDivision Multiplexing (TDM) adapted to divide and use time resources andFrequency Division Multiplexing (FDM) adapted to divide and usefrequency resources. That is, TDM is a method of assigning time segmentsto respective services, and FDM is a technique for assigning frequencyresource segments to respective services and then using them. Recently,there is an urgent need for new multiplexing technology that isapplicable to a next generation broadcasting system and provides greaterflexibility and performance than TDM and FDM.

The decoding process can be greatly changed according to the timeinterleaving modes corresponding to the physical layer pipes when oneservice is transmitted using a plurality of physical layer pipes.

DISCLOSURE Technical Problem

An object of the present invention is to enable the layered divisionmultiplexing using a core layer physical layer pipe and an enhancedlayer physical layer pipe to be performed efficiently using a propersignaling parameter.

Furthermore, an object of the present invention is to allow receivers torestore the core layer physical layer pipe and the enhanced layerphysical layer pipe which are layered division multiplexed withoutoverly large burden of implementation.

Technical Solution

In order to accomplish the above objects, the present invention providesan apparatus for generating broadcast signal frame, including: acombiner configured to generate a multiplexed signal by combining a corelayer signal and an enhanced layer signal; a power normalizer configuredto reduce power of the multiplexed signal to a power level correspondingto the core layer signal; a time interleaver configured to generate atime-interleaved signal by performing time-interleaving that is appliedto both the core layer signal and the enhanced layer signal; and a framebuilder configured to generate a broadcast signal frame including apreamble for signaling start position information and size informationfor each of Physical Layer Pipes (PLPs). In this case, the PhysicalLayer Pipes (PLPs) include a core layer physical layer pipecorresponding to the core layer signal and an enhanced layer physicallayer pipe corresponding to the enhanced layer signal. In this case,injection level information corresponding to the enhanced layer signalis signaled corresponding to the enhanced layer physical layer pipe.

In this case, the Physical Layer Pipes may include two or more enhancedlayer physical layer pipes and the two or more enhanced layer physicallayer pipes may have the same injection level information when the corelayer physical layer pipe is layered division multiplexed with the twoor more enhanced layer physical layer pipes.

In this case, the injection level information may correspond to a valueat least 3 dB larger than a required SNR value corresponding to the corelayer signal before the combining.

In this case, the Physical Layer Pipes may be multiplexed by FrequencyDivision Multiplexing (FDM), and signaling information corresponding tothe Frequency Division Multiplexing may be signaled only for core layerphysical layer pipes and may not be signaled for enhanced layer physicallayer pipes.

In this case, the signaling information corresponding to the FrequencyDivision Multiplexing may include at least one of physical layer pipetype information (L1D_plp_type), physical layer pipe subslice intervalinformation (L1D_plp_subslice_interval) and physical layer pipe subslicenumber information (L1D_plp_num_subslices).

In this case, the enhanced layer physical layer pipe may follow a cellwriting order corresponding to the signaling information correspondingto the Frequency Division Multiplexing of the core layer physical layerpipe to which the enhanced layer physical layer pipe is layered divisionmultiplexed when the Frequency Division Multiplexing is performed.

In this case, the enhanced layer physical layer pipes which areFrequency Division Multiplexed may have a total size not exceeding 2²⁰cells.

In this case, the Physical Layer Pipes may include two or more corelayer physical layer pipes and a time interleaving mode corresponding tothe time interleaver may be one of hybrid time interleaving mode or notime interleaving mode when the enhanced layer physical layer pipe islayered division multiplexed to the two or more core layer physicallayer pipes.

In this case, the two or more core layer physical layer pipes may haveinteger numbers of FEC blocks when the no time interleaving mode isused.

In this case, the two or more core layer physical layer pipes may havethe same time interleaving block size or time interleaving block sizes(the differences between the time interleaving block sizes are less thana predetermined value) when the hybrid time interleaving mode is used.

In this case, the Physical Layer Pipes may have the start positioninformation and the size information which are set not to have anyduration where the layered division multiplexing is not applied in thecore layer physical layer pipe which is layered division multiplexedwith the enhanced layer physical layer pipe.

In this case, the core layer physical layer pipe may be modulated by anyone of QPSK, 16 QAM and/or 64 QAM, and may be encoded by a code rate ofup to 7/15 when the 64 QAM is used.

In this case, up to four physical layer pipes may be used for onecomplete delivered product.

Furthermore, an embodiment of the present invention provides a method ofgenerating broadcast signal frame, including: generating a multiplexedsignal by combining a core layer signal and an enhanced layer signal;reducing power of the multiplexed signal to a power level correspondingto the core layer signal; generating a time-interleaved signal byperforming time-interleaving that is applied to both the core layersignal and the enhanced layer signal; and generating a broadcast signalframe including a preamble for signaling start position information andthe size information for each of Physical Layer Pipes (PLPs). In thiscase, the Physical Layer Pipes include a core layer physical layer pipecorresponding to the core layer signal and an enhanced layer physicallayer pipe corresponding to the enhanced layer signal. In this case,injection level information corresponding to the enhanced layer signalis signaled corresponding to the enhanced physical layer pipe.

In this case, the Physical Layer Pipes may include two or more enhancedlayer physical layer pipes and the two or more enhanced layer physicallayer pipes may have the same injection level information when the corelayer physical layer pipe is layered division multiplexed with the twoor more enhanced layer physical layer pipes.

Advantageous Effects

According to the present invention, the layered division multiplexingusing the core layer physical layer pipe and the enhanced layer physicallayer pipe can be effectively performed by using proper signalingparameters.

Furthermore, according to the present invention, the core layer physicallayer pipe and the enhanced layer physical layer pipe which are layereddivision multiplexed can be restored without overly large burden ofimplementation in receivers.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention;

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention;

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1;

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame;

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4;

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4;

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1;

FIG. 8 is a block diagram showing an example of the signal demultiplexershown in FIG. 1;

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder and the enhanced layer symbol extractor shown in FIG. 8;

FIG. 10 is a block diagram showing another example of the core layerBICM decoder and the enhanced layer symbol extractor shown in FIG. 8;

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder and the enhanced layer symbol extractor shown in FIG.8;

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1;

FIG. 13 is a diagram showing an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal;

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention;

FIG. 15 is a diagram showing a structure of a super-frame which includesbroadcast signal frames according to an embodiment of the presentinvention;

FIG. 16 is a diagram showing an example of a LDM frame includingmultiple-physical layer pipes and using LDM of two layers;

FIG. 17 is a diagram showing another example of a LDM frame includingmultiple-physical layer pipes and using LDM of two layers;

FIG. 18 is a diagram showing an application example of a LDM frame usingmultiple-physical layer pipes and LDM of two layers;

FIG. 19 is a diagram showing another application example of a LDM frameusing multiple-physical layer pipes and LDM of two layers;

FIG. 20 is a diagram showing an example in which a convolutional timeinterleaver is used;

FIG. 21 is a diagram showing another example in which a convolutionaltime interleaver is used;

FIG. 22 is a diagram showing an example in which a hybrid timeinterleaver is used;

FIG. 23 is a diagram showing time interleaver groups in the example ofFIG. 22;

FIGS. 24-26 are diagrams showing a process for calculating a size of theincomplete FEC block in the example of FIG. 23;

FIG. 27 is a diagram for explaining the number of bits required forL1D_plp_fec_block_start when L1D_plp_TI_mode=“00”;

FIGS. 28 and 29 are diagrams for explaining the number of bits requiredfor L1D_plp_CTI_fec_block_start when L1D_plp_TI_mode=“01”;

FIG. 30 is a diagram showing an insertion of Enhanced Layer dummy valueswhen the HTI mode is used with Layered-Division Multiplexing;

FIG. 31 is a diagram showing an example of the shift register used forgenerating the dummy values according to the exemplary embodiment of thepresent invention;

FIG. 32 is a diagram showing types of the time interleaving mode;

FIG. 33 is a diagram showing a case where the intra-subframeinterleaving and the inter-subframe interleaving are used at the sametime;

FIG. 34 is a diagram showing subframes in case that the intra-subframeinterleaving and the inter-subframe interleaving are used at the sametime;

FIG. 35 is a diagram showing a case where time interleaving units whichare different one another are used at the same time;

FIG. 36 is a diagram showing subframes in case that the same timeinterleaving unit is used at the same time;

FIG. 37 is a diagram showing a case where one complete delivered productis composed of a plurality of physical layer pipes;

FIG. 38 is a block diagram showing an example of the time interleaver inFIG. 3 or FIG. 7;

FIG. 39 is a diagram showing a writing operation of the twisted blockinterleaver in FIG. 38;

FIG. 40 is a diagram showing a reading operation of the twisted blockinterleaver in FIG. 38;

FIG. 41 is a block diagram showing an example of the convolutional delayline in FIG. 38;

FIG. 42 is a diagram showing an example of operation of the twistedblock interleaver in FIG. 38;

FIG. 43 is a diagram showing an example of operation of theconvolutional delay line in FIG. 38;

FIG. 44 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 43;

FIG. 45 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 42;

FIG. 46 is a diagram showing another example of operation of the twistedblock interleaver in FIG. 38;

FIG. 47 is a diagram showing another example of operation of theconvolutional delay line in FIG. 38;

FIG. 48 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 47;

FIG. 49 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 46;

FIG. 50 is a diagram showing initial values of the FIFO registerincluded in the convolutional delay line;

FIG. 51 is a block diagram showing an example of the time deinterleaverin FIG. 8 or FIG. 12;

FIG. 52 is an operation flowchart showing a method of time interleavingaccording to an embodiment of the present invention;

FIG. 53 is a diagram showing the layered division multiplexed physicallayer pipes with respect to before time-interleaving;

FIG. 54 is a diagram showing the layered division multiplexed physicallayer pipes with respect to after time-interleaving;

FIG. 55 is a diagram showing the subframe including layered divisionmultiplexed physical layer pipes;

FIG. 56 is a diagram showing the first timing of the convolutional delayline performing the time interleaving corresponding to the physicallayer pipes shown in FIGS. 53˜55;

FIG. 57 is a diagram showing the second timing of the convolutionaldelay line performing the time interleaving corresponding to thephysical layer pipes shown in FIGS. 53˜55;

FIG. 58 is a diagram showing the third timing of the convolutional delayline performing the time interleaving corresponding to the physicallayer pipes shown in FIGS. 53˜55;

FIG. 59 is a diagram showing the first timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55;

FIG. 60 is a diagram showing the second timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55;

FIG. 61 is a diagram showing the third timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55;

FIG. 62 is a diagram showing signaling definitions of L1D_plp_start andL1D_plp_size;

FIG. 63 is a diagram showing the time interleaving group assignment formultiple core physical layer pipes;

FIG. 64 is a diagram showing two enhanced layer physical layer pipeswhich are injected into a single core layer physical layer pipe;

FIG. 65 is a diagram showing an example of undesirable LDMconfiguration;

FIG. 66 is a diagram showing another example of undesirable LDMconfiguration;

FIG. 67 is a diagram showing an example of allowed LDM configuration inthe CTI mode;

FIG. 68 is a diagram showing another example of allowed LDMconfiguration in the CTI mode;

FIG. 69 is a diagram showing an example of allowed LDM configuration inthe HTI mode;

FIG. 70 is a diagram showing an example of use of time interleavingblocks for HTI-based LTDM or LFDM configurations;

FIG. 71 is a diagram showing an example of FLDM configuration; and

FIG. 72 is a diagram showing an example of LFDM configuration.

MODE FOR INVENTION

The present invention will be described in detail below with referenceto the accompanying drawings. In the description, redundant descriptionsand descriptions of well-known functions and configurations that havebeen deemed to make the gist of the present invention unnecessarilyobscure will be omitted below. The embodiments of the present inventionare provided to fully describe the present invention to persons havingordinary knowledge in the art to which the present invention pertains.Accordingly, the shapes, sizes, etc. of components in the drawings maybe exaggerated to make the description obvious.

Preferred embodiments of the present invention are described in detailbelow with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention.

Referring to FIG. 1, a broadcast signal transmission/reception systemaccording to the embodiment of the present invention includes abroadcast signal transmission apparatus 110, a wireless channel 120, anda broadcast signal reception apparatus 130.

The broadcast signal transmission apparatus 110 includes an apparatusfor generating broadcast signal frame 111 which generate the broadcastsignal frame by multiplexing core layer data and enhanced layer data,and an OFDM transmitter 113.

The apparatus 111 combines a core layer signal corresponding to corelayer data and an enhanced layer signal corresponding to enhanced layerdata, performs power-normalizing for reducing power of the combinedsignal to a power level corresponding to the core layer signal, andgenerating a time-interleaved signal by performing time interleavingafter performing the power-normalizing.

In this case, the core layer signal and the enhanced layer signal may becombined at different power levels. In this case, the time interleavingmay be applied to both the core layer signal and the enhanced layersignal. In this case, the apparatus 111 may generate a broadcast signalframe including a bootstrap and a preamble using the time-interleavedsignal. In this case, the broadcast signal frame may be an ATSC 3.0frame.

In this case, the preamble may be for signaling the start positioninformation and the size information for each of the Physical LayerPipes (PLPs).

In this case, the Physical Layer Pipes (PLPs) may include the core layerphysical layer pipe corresponding to the core layer signal and theenhanced layer physical layer pipe corresponding to the enhanced layersignal.

In this case, injection level information corresponding to the enhancedlayer signal may be signaled corresponding to the enhanced layerphysical layer pipe.

According to an embodiment, the apparatus 111 may time-interleave onelayer signal (BICM output signal) and generate the broadcast signalframe without combining two layer signals.

In this case, the preamble may signal a time interleaving modecorresponding to the time interleaver for each of physical layer pipes(PLPs).

In this case, the physical layer pipes may include one enhanced layerphysical layer pipe and a plurality of core layer physical layer pipeswhich are layered-division multiplexed with the one enhanced layerphysical layer pipe.

In this case, the time interleaving mode corresponding to the enhancedlayer physical layer pipe may be the same as time interleaving modescorresponding to the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed.

In this case, the time interleaving modes corresponding to the corelayer physical layer pipes with which the enhanced layer physical layerpipe is layered-division multiplexed may be all no time interleavingmode or all hybrid time interleaving mode.

In this case, the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayall use an intra-subframe interleaving mode, when the time interleavingmodes corresponding to the core layer physical layer pipes with whichthe enhanced layer physical layer pipe is layered-division multiplexedare all hybrid time interleaving mode.

In this case, each of core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayconsist of an integer number of FEC blocks within each subframe, whenthe time interleaving modes corresponding to the core layer physicallayer pipes with which the enhanced layer physical layer pipe islayered-division multiplexed are all no time interleaving mode.

In this case, all of available data cells of the subframe may be filledwith dummy modulation values first and then the actual physical layerpipe data may be overwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (x¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

In this case, the physical layer pipes may include a plurality of corelayer physical layer pipes corresponding to one complete deliveredproduct, and the core layer physical layer pipes may be not layereddivision multiplexed.

In this case, each of the core layer physical layer pipes may use eithera no time interleaving mode or a hybrid time interleaving mode as thetime interleaving mode, and may not use a convolutional interleavingmode.

In this case, all of the core layer physical layer pipes may use anintra-subframe interleaving mode or all of the core layer physical layerpipes may use an inter-subframe interleaving mode, when all of the corelayer physical layer pipes use the hybrid time interleaving mode as thetime interleaving mode.

In this case, all of the core layer physical layer pipes may beconfigured with the same value of L1D_plp_HTI_inter_subframe when all ofthe core layer physical layer pipes use the hybrid time interleavingmode as the time interleaving mode.

In this case, all of the core layer physical layer pipes may use thesame time interleaving unit (N_(IU)) when all of the core layer physicallayer pipes use the hybrid time interleaving mode as the timeinterleaving mode and the inter-subframe interleaving mode.

In this case, any of the core layer physical layer pipes configured withthe hybrid time interleaving mode may use the intra-subframeinterleaving mode when at least one of the core layer physical layerpipes uses the no time interleaving mode as the time interleaving mode.

In this case, the one complete delivered product may correspond to atleast one subframe, and the subframe may be filled with dummy modulationvalues first and then the actual physical layer pipe data may beoverwritten for generating the subframe.

In this case, the time interleaving may use one of time interleavergroups, and a boundary between the time interleaver groups may be aboundary between Physical Layer Pipes (PLPs) of a core layercorresponding to the core layer signal. That is, one of the boundariesbetween the Physical Layer Pipes of the core layer may be the boundarybetween the time interleaver groups.

In this case, enhanced layer data corresponding to the one of the timeinterleaver groups include dummy values.

In this case, the dummy values may be inserted after the actual datacells of the last Enhanced PLP in a PLP group so that the total numberof Enhanced Layer cells in the PLP group is the same as the total numberof Core Layer cells in the PLP group.

In this case, the dummy values may be not inserted in core layer data.

In this case, the dummy values may be inserted after core layer andenhanced layer BICMs and before the core layer signal and the enhancedlayer signal are combined.

In this case, the dummy values may correspond to a predeterminedscrambling sequence.

In this case, the scrambling sequence may be modulated by using the sameconstellation mapping that is used for the last Enhanced PLP.

In this case, the dummy values may have the same power as the lastEnhanced PLP.

In this case, the scrambling sequence may be generated by a 16-bit shiftregister corresponding to a predetermined generator polynomial.

In this case, the scrambling sequence may be generated by a generatorpolynomial corresponding to 1+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (X¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

The OFDM transmitter 113 transmits the generated broadcast signal frameusing an OFDM communication method via an antenna 117, thereby allowingthe transmitted OFDM signal to be received via the antenna 137 of thebroadcast signal reception apparatus 130 over the wireless channel 120.

The broadcast signal reception apparatus 130 includes an OFDM receiver133 and a signal demultiplexer 131. When the signal transmitted over thewireless channel 120 is received via the antenna 137, the OFDM receiver133 receives an OFDM signal via synchronization, channel estimation andequalization.

In this case, the OFDM receiver 133 may detect and demodulate thebootstrap from the OFDM signal, demodulate the preamble usinginformation included in the bootstrap, and demodulate the super-imposedpayload using information included in the preamble.

The signal demultiplexer 131 restores the core layer data from thesignal (super-imposed payload) received via the OFDM receiver 133 first,and then restores the enhanced layer data via cancellation correspondingto the restored core layer data. In this case, the signal demultiplexer131 may generate a broadcast signal frame first, may restore thebootstrap, may restore the preamble using the information included inthe bootstrap, and may use the signaling information included in thepreamble for the restoration of a data signal. In this case, thesignaling information may be L1 signaling information and may includeinjection level information, normalizing factor information, etc.

In this case, the preamble may include a time interleaving modecorresponding to the time interleaver for each physical layer pipe.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble on the basis of the core layer.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing the layeridentification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

In this case, the time interleaver information may be signaled on thebasis of the core layer.

In this case, the time interleaver may correspond to a hybrid timeinterleaver. In this case, Physical Layer Pipes (PLPs) of a core layerand an enhanced layer may include only complete FEC blocks.

In this case, the preamble may be for signaling information foridentifying a part of a FEC block in the enhanced layer in case that theboundary between the time interleaver groups does not correspond to aboundary between FEC blocks in the enhanced layer, the FEC blockcorresponding to the boundary between the time interleaver groups.

In this case, the information for identifying the part of the FEC blockmay include at least one of start position information of a PhysicalLayer Pipe (PLP) in the core layer, start position information of aPhysical Layer Pipe (PLP) in the enhanced layer, modulation informationcorresponding to the enhanced layer, and FEC type informationcorresponding to the enhanced layer.

In this case, the start position information of the Physical Layer Pipe(PLP) may correspond to an index of a first data cell of the PhysicalLayer Pipe (PLP).

In this case, the modulation information may be signaled only if the FECtype information satisfies a predetermined condition.

In this case, the enhanced layer signal may correspond to enhanced layerdata that is restored based on cancellation corresponding to restorationof core layer data corresponding to the core layer signal.

In this case, the time interleaver may correspond to a convolutionaltime interleaver, the time interleaver groups may include the PhysicalLayer Pipe (PLP) which includes an incomplete FEC block, and thepreamble may be for signaling start position information of a firstcomplete FEC block in the Physical Layer Pipe (PLP).

In this case, the time interleaver may perform the interleaving by usingone of a plurality of operation modes.

In this case, the operation modes may include a first mode correspondingto no time interleaving, a second mode for performing a Convolutionaltime interleaving and a third mode for performing a Hybrid timeinterleaving.

In this case, the preamble may include a field indicating a startposition of a first complete FEC block corresponding to a currentPhysical Layer Pipe for the first mode and the second mode, and may notinclude the field indicating the start position of the first FEC blockfor the third mode. In this case, the field indicating the startposition may indicate the start position of the first FEC block startingin a current Physical Layer Pipe during a current subframe.

In this case, the field indicating the start position of the first FECblock may be one of a first field used in the first mode and a secondfield used in the second mode, and the first field and the second fieldmay have different lengths.

In this case, the length of the second field may be longer than thelength of the first field.

In this case, the length of the first field may be determined based on alength of a LDPC codeword and a modulation order and the length of thesecond field may be determined not only by the length of the LDPCcodeword and the modulation order but also by further considering adepth of a Convolutional time interleaver.

In this case, the length of the first field may be 15 bits and thelength of the second field may be 22 bits.

In this case, the first field and the second field may be separatelysignaled for each of a core layer corresponding to the core layer signaland an enhanced layer corresponding to the enhanced layer signal.

As will be described in detail later, the apparatus 111 shown in FIG. 1may include a combiner configured to generate a multiplexed signal bycombining a core layer signal and an enhanced layer signal; a powernormalizer configured to perform power-normalizing for reducing thepower of the multiplexed signal to a power level corresponding to thecore layer signal; a time interleaver configured to generate atime-interleaved signal by performing time interleaving after performingthe power-normalizing; and a frame builder configured to generate abroadcast signal frame including a preamble for signaling start positioninformation and size information for each of Physical Layer Pipes(PLPs). In this case, the Physical Layer Pipes may include a core layerphysical layer pipe corresponding to the core layer signal and anenhanced layer physical layer pipe corresponding to the enhanced layersignal. In this case, injection level information corresponding to theenhanced layer signal may be signaled corresponding to the enhancedlayer physical layer pipe. In this case, the time interleaver may useone of time interleaver groups, and enhanced layer data corresponding tothe one of the time interleaver groups may include dummy values. In thiscase, the broadcast signal transmission apparatus 110 shown in FIG. 1may be viewed as including: a combiner configured to generate amultiplexed signal by combining a core layer signal and an enhancedlayer signal; a power normalizer configured to perform power-normalizingfor reducing the power of the multiplexed signal to a power levelcorresponding to the core layer signal; a time interleaver configured togenerate a time-interleaved signal by performing time interleaving afterperforming the power-normalizing; a frame builder configured to generatea broadcast signal frame including a preamble for signaling startposition information and size information for each of Physical LayerPipes (PLPs); and an OFDM transmitter configured to transmit thebroadcast signal frame using OFDM communication scheme through anantenna. In this case, the Physical Layer Pipes may include a core layerphysical layer pipe corresponding to the core layer signal and anenhanced layer physical layer pipe corresponding to the enhanced layersignal. In this case, injection level information corresponding to theenhanced layer signal may be signaled corresponding to the enhancedlayer physical layer pipe. In this case, the time interleaver may useone of time interleaver groups, and enhanced layer data corresponding tothe one of the time interleaver groups may include dummy values.

According to an embodiment, the apparatus 111 shown in FIG. 1 mayinclude a time interleaver configured to generate a time-interleavedsignal by performing time-interleaving on a BICM output signal; and aframe builder configured to generate a broadcast signal frame includinga preamble for signaling start position information and size informationfor each of Physical Layer Pipes (PLPs), in case of a single layer. Inthis case, the Physical Layer Pipes may include a core layer physicallayer pipe corresponding to the core layer signal and an enhanced layerphysical layer pipe corresponding to the enhanced layer signal. In thiscase, injection level information corresponding to the enhanced layersignal may be signaled corresponding to the enhanced layer physicallayer pipe. In this case, the BICM output signal may be an output signalof a BICM apparatus which will be described later. In this case, thebroadcast signal transmission apparatus 110 shown in FIG. 1 may beviewed as including: a time interleaver configured to generate atime-interleaved signal by performing time-interleaving on a BICM outputsignal; a frame builder configured to generate a broadcast signal frameincluding a preamble for signaling start position information and sizeinformation for each of Physical Layer Pipes (PLPs); and an OFDMtransmitter configured to transmit the broadcast signal frame using OFDMcommunication scheme through an antenna. In this case, the PhysicalLayer Pipes may include a core layer physical layer pipe correspondingto the core layer signal and an enhanced layer physical layer pipecorresponding to the enhanced layer signal. In this case, injectionlevel information corresponding to the enhanced layer signal may besignaled corresponding to the enhanced layer physical layer pipe.

As will be described in detail later, the signal demultiplexer shown inFIG. 1 may include a time deinterleaver configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal corresponding to a broadcast signal frame; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller. In this case, the broadcast signalreception apparatus 130 shown in FIG. 1 may be viewed as including: anOFDM receiver configured to generate a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; a timedeinterleaver configured to generate a time-deinterleaved signal byapplying time deinterleaving to the received signal; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller.

In this case, the time deinterleaver may use one of time interleavergroups, and enhanced layer data corresponding to the one of the timeinterleaver groups may include dummy values.

In this case, the time deinterleaver may correspond to the timeinterleaving mode.

In this case, the preamble may include the time interleaving modecorresponding to the time interleaver for each physical layer pipe.

Although not explicitly shown in FIG. 1, a broadcast signaltransmission/reception system according to an embodiment of the presentinvention may multiplex/demultiplex one or more pieces of extensionlayer data in addition to the core layer data and the enhanced layerdata. In this case, the extension layer data may be multiplexed at apower level lower than that of the core layer data and the enhancedlayer data. Furthermore, when two or more extension layers are included,the injection power level of a second extension layer may be lower thanthe injection power level of a first extension layer, and the injectionpower level of a third extension layer may be lower than the injectionpower level of the second extension layer.

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention.

Referring to FIG. 2, in the broadcast signal transmission/receptionmethod according to the embodiment of the present invention, a corelayer signal and an enhanced layer signal are combined for multiplexingthem to generate a broadcast signal frame at step S210. In this case,the core layer signal and the enhanced layer signal may be combined atdifferent power levels. In this case, the broadcast signal frame may begenerated by performing time interleaving, and the preamble of thebroadcast signal frame may include a time interleaving modecorresponding to the time interleaving for each of the physical layerpipes (PLPs).

According to an embodiment, the time interleaved signal may be generatedby performing time interleaving on the BICM output signal and thebroadcast signal frame which include a preamble for signaling a timeinterleaving mode corresponding to the time interleaving for each of thephysical layer pipes may be generated at step S210.

In this case, the preamble may be for signaling start positioninformation and size information for each of Physical Layer Pipes(PLPs). In this case, the Physical Layer Pipes may include a core layerphysical layer pipe corresponding to the core layer signal and anenhanced layer physical layer pipe corresponding to the enhanced layersignal.

In this case, the physical layer pipes may include a plurality of corelayer physical layer pipes corresponding to one complete deliveredproduct, and the core layer physical layer pipes may be not layereddivision multiplexed.

In this case, each of the core layer physical layer pipes may use eithera no time interleaving mode or a hybrid time interleaving mode as thetime interleaving mode, and may not use a convolutional interleavingmode.

In this case, all of the core layer physical layer pipes may use anintra-subframe interleaving mode or all of the core layer physical layerpipes may use an inter-subframe interleaving mode, when all of the corelayer physical layer pipes use the hybrid time interleaving mode as thetime interleaving mode.

In this case, all of the core layer physical layer pipes may beconfigured with the same value of L1D_plp_HTI_inter_subframe when all ofthe core layer physical layer pipes use the hybrid time interleavingmode as the time interleaving mode.

In this case, all of the core layer physical layer pipes may use thesame time interleaving unit (N_(IU)) when all of the core layer physicallayer pipes use the hybrid time interleaving mode as the timeinterleaving mode and the inter-subframe interleaving mode.

In this case, any of the core layer physical layer pipes configured withthe hybrid time interleaving mode may use the intra-subframeinterleaving mode when at least one of the core layer physical layerpipes uses the no time interleaving mode as the time interleaving mode.

In this case, the one complete delivered product may correspond to atleast one subframe, and the subframe may be filled with dummy modulationvalues first and then the actual physical layer pipe data may beoverwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+x+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the physical layer pipes may include one enhanced layerphysical layer pipe and a plurality of core layer physical layer pipeswhich are layered-division multiplexed with the one enhanced layerphysical layer pipe.

In this case, the time interleaving mode corresponding to the enhancedlayer physical layer pipe may be the same as time interleaving modescorresponding to the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed.

In this case, the time interleaving modes corresponding to the corelayer physical layer pipes with which the enhanced layer physical layerpipe is layered-division multiplexed may be all no time interleavingmode or all hybrid time interleaving mode.

In this case, the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayall use an intra-subframe interleaving mode, when the time interleavingmodes corresponding to the core layer physical layer pipes with whichthe enhanced layer physical layer pipe is layered-division multiplexedare all hybrid time interleaving mode.

In this case, each of core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayconsist of an integer number of FEC blocks within each subframe, whenthe time interleaving modes corresponding to the core layer physicallayer pipes with which the enhanced layer physical layer pipe islayered-division multiplexed are all no time interleaving mode.

In this case, all of available data cells of the subframe may be filledwith dummy modulation values first and then the actual physical layerpipe data may be overwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (x¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

In this case, the broadcast signal frame generated at step S210 mayinclude the bootstrap, the preamble and a super-imposed payload. In thiscase, at least of the bootstrap and the preamble may include L1signaling information. In this case, the L1 signaling information mayinclude injection level information and normalizing factor information.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble on the basis of a core layer.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing the layeridentification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

In this case, the time interleaver information may be signaled on thebasis of the core layer.

In this case, the generating the time-interleaved signal may use ahybrid time interleaver for performing the interleaving.

In this case, the Physical Layer Pipes (PLPs) of a core layer and anenhanced layer may include only complete FEC blocks.

In this case, the preamble may be for signaling information foridentifying a part of a FEC block of the enhanced layer in case that theboundary between the time interleaver groups does not correspond to aboundary between FEC blocks of the enhanced layer, the FEC blockcorresponding to the boundary between the time interleaver groups.

In this case, the information for identifying the part of the FEC blockmay include at least one of start position information of a PhysicalLayer Pipe (PLP) in the core layer, start position information of aPhysical Layer Pipe (PLP) in the enhanced layer, modulation informationcorresponding to the enhanced layer, and FEC type informationcorresponding to the enhanced layer.

In this case, the start position information of the Physical Layer Pipe(PLP) may correspond to an index of a first data cell of the PhysicalLayer Pipe (PLP).

In this case, the modulation information may be signaled only if the FECtype information satisfies a predetermined condition.

In this case, the enhanced layer signal corresponds to enhanced layerdata that may be restored based on cancellation corresponding torestoration of core layer data corresponding to the core layer signal.

In this case, the generating the time-interleaved signal may use aconvolutional time interleaver for performing the interleaving, the timeinterleaver groups may include the Physical Layer Pipe (PLP) whichincludes an incomplete FEC block, and the preamble may be for signalingstart position information of a first complete FEC block in the PhysicalLayer Pipe (PLP).

In this case, the interleaving may use one of time interleaver groups,and enhanced layer data corresponding to the one of the time interleavergroups may include dummy values.

In this case, the dummy values may be inserted after the actual datacells of the last Enhanced PLP in a PLP group so that the total numberof Enhanced Layer cells in the PLP group is the same as the total numberof Core Layer cells in the PLP group.

In this case, the dummy values may be not inserted in core layer data.

In this case, the dummy values may be inserted after core layer andenhanced layer BICMs and before the core layer signal and the enhancedlayer signal are combined.

In this case, the dummy values may correspond to a predeterminedscrambling sequence.

In this case, the scrambling sequence may be modulated by using the sameconstellation mapping that is used for the last Enhanced PLP.

In this case, the dummy values may have the same power as the lastEnhanced PLP.

In this case, the scrambling sequence may be generated by a 16-bit shiftregister corresponding to a predetermined generator polynomial.

In this case, the scrambling sequence may be generated by a generatorpolynomial corresponding to 1+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (X¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

In this case, the interleaving may be performed by using one of aplurality of operation modes.

In this case, the operation modes may include a first mode correspondingto no time interleaving, a second mode for performing a Convolutionaltime interleaving and a third mode for performing a Hybrid timeinterleaving.

In this case, the preamble may include a field indicating a startposition of a first complete FEC block corresponding to a currentPhysical Layer Pipe for the first mode and the second mode, and may notinclude the field indicating the start position of the first FEC blockfor the third mode.

In this case, the field indicating the start position of the first FECblock may be one of a first field used in the first mode and a secondfield used in the second mode, and the first field and the second fieldmay have different lengths.

In this case, the length of the second field may be longer than thelength of the first field.

In this case, the length of the first field may be determined based on alength of a LDPC codeword and a modulation order and the length of thesecond field may be determined not only by the length of the LDPCcodeword and the modulation order but also by further considering adepth of a Convolutional time interleaver.

In this case, the length of the first field may be 15 bits and thelength of the second field may be 22 bits.

In this case, the first field and the second field may be separatelysignaled for each of a core layer corresponding to the core layer signaland an enhanced layer corresponding to the enhanced layer signal.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the broadcastsignal frame is OFDM transmitted at step S220.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the transmittedsignal is OFDM received at step S230.

In this case, at step S230, synchronization, channel estimation andequalization may be performed.

In this case, the bootstrap may be restored, the preamble may berestored using a signal included in the restored bootstrap, and the datasignal may be restored using the signaling information included in thepreamble at step S230.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, core layer data isrestored from the received signal at step S240.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, enhanced layerdata is restored via the cancellation of the core layer signal at stepS250.

In particular, steps S240 and S250 shown in FIG. 2 may correspond todemultiplexing operations corresponding to step S210.

As will be described in detail later, step S210 shown in FIG. 2 mayinclude generating a time-interleaved signal by performing timeinterleaving on a BICM output signal; and generating a broadcast signalframe including a preamble for signaling a time interleaving modecorresponding to the time interleaving for each of the physical layerpipes (PLPs) in case of a single layer. In this case, the broadcastsignal transmission method of steps S210 and S220 may be viewed asincluding generating a time-interleaved signal by performing timeinterleaving on a BICM output signal; generating a broadcast signalframe including a preamble for signaling a time interleaving modecorresponding to the time interleaving for each of the physical layerpipes (PLPs); and transmitting the broadcast signal frame using an OFDMcommunication scheme through an antenna in case of a single layer.

As will be described in detail later, step S210 shown in FIG. 2 mayinclude generating a multiplexed signal by combining a core layer signaland an enhanced layer signal; performing power-normalizing for reducingthe power of the multiplexed signal to a power level corresponding tothe core layer signal; generating a time-interleaved signal byperforming time interleaving after performing the power-normalizing; andgenerating a broadcast signal frame including a preamble for signaling atime interleaving mode corresponding to the time interleaving for eachof the physical layer pipes (PLPs). In this case, the time interleavingmay use one of time interleaver groups, and enhanced layer datacorresponding to the one of time interleaver groups may include dummyvalues. In this case, the broadcast signal transmission method of stepsS210 and S220 may be viewed as including generating a multiplexed signalby combining a core layer signal and an enhanced layer signal;performing power-normalizing for reducing the power of the multiplexedsignal to a power level corresponding to the core layer signal;generating a time-interleaved signal by performing time interleavingafter performing the power-normalizing; generating a broadcast signalframe including a preamble for signaling a time interleaving modecorresponding to the time interleaving for each of the physical layerpipes (PLPs); and transmitting the broadcast signal frame using an OFDMcommunication scheme through an antenna. In this case, the timeinterleaving may use one of time interleaver groups, and enhanced layerdata corresponding to the one of the time interleaver groups may includedummy values.

As will be described in detail later, steps S240 and S250 shown in FIG.2 may include generating a time-deinterleaved signal by applying timedeinterleaving to a received signal corresponding to a broadcast signalframe; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced signal. In this case, a broadcast signalreception method according to an embodiment of the present invention maybe viewed as including: generating a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; generatinga time-deinterleaved signal by applying time deinterleaving to thereceived signal; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced layer signal.

In this case, the time deinterleaving may correspond to the timeinterleaving mode.

In this case, the preamble may include the time interleaving modecorresponding to the time interleaving for each physical layer pipe.

In this case, the time deinterleaving may perform the deinterleaving byusing one of a plurality of operation modes.

In this case, the time deinterleaving may use one of time interleavergroups, and enhanced layer data corresponding to the one of timeinterleaver groups may include dummy values.

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1.

Referring to FIG. 3, the apparatus for generating broadcast signal frameaccording to an embodiment of the present invention may include a corelayer BICM unit 310, an enhanced layer BICM unit 320, an injection levelcontroller 330, a combiner 340, a power normalizer 345, and a timeinterleaver 350, a signaling generation unit 360, and a frame builder370.

Generally, a BICM device includes an error correction encoder, a bitinterleaver, and a symbol mapper. Each of the core layer BICM unit 310and the enhanced layer BICM unit 320 shown in FIG. 3 may include anerror correction encoder, a bit interleaver, and a symbol mapper. Inparticular, each of the error correction encoders (the core layer FECencoder, and the enhanced layer FEC encoder) shown in FIG. 3 may beformed by connecting a BCH encoder and an LDPC encoder in series. Inthis case, the input of the error correction encoder is input to the BCHencoder, the output of the BCH encoder is input to the LDPC encoder, andthe output of the LDPC encoder may be the output of the error correctionencoder.

As shown in FIG. 3, core layer data and enhanced layer data pass throughrespective different BICM units, and are then combined by the combiner340. That is, the term “Layered Division Multiplexing (LDM)” used hereinmay refer to combining the pieces of data of a plurality of layers intoa single piece of data using differences in power and then transmittingthe combined data.

That is, the core layer data passes through the core layer BICM unit310, the enhanced layer data passes through the enhanced layer BICM unit320 and then the injection level controller 330, and the core layer dataand the enhanced layer data are combined by the combiner 340. In thiscase, the enhanced layer BICM unit 320 may perform BICM encodingdifferent from that of the core layer BICM unit 310. That is, theenhanced layer BICM unit 320 may perform higher bit rate errorcorrection encoding or symbol mapping than the core layer BICM unit 310.Furthermore, the enhanced layer BICM unit 320 may perform less robusterror correction encoding or symbol mapping than the core layer BICMunit 310.

For example, the core layer error correction encoder may exhibit a lowerbit rate than the enhanced layer error correction encoder. In this case,the enhanced layer symbol mapper may be less robust than the core layersymbol mapper.

The combiner 340 may be viewed as functioning to combine the core layersignal and the enhanced layer signal. In this case, the combiner 340 maycombine the core layer signal and the enhanced layer signal at differentpower levels. In an embodiment, power level adjustment may be performedon the core layer signal rather than the enhanced layer signal. In thiscase, the power of the core layer signal may be adjusted to be higherthan the power of the enhanced layer signal.

The core layer data may use forward error correction (FEC) code having alow code rate in order to perform robust reception, while the enhancedlayer data may use FEC code having a high code rate in order to achievea high data transmission rate.

That is, the core layer data may have a broader coverage than theenhanced layer data in the same reception environment.

The enhanced layer data having passed through the enhanced layer BICMunit 320 is adjusted in gain (or power) by the injection levelcontroller 330, and is combined with the core layer data by the combiner340.

That is, the injection level controller 330 generates a power-reducedenhanced layer signal by reducing the power of the enhanced layersignal. In this case, the magnitude of the signal adjusted by theinjection level controller 330 may be determined based on an injectionlevel. In this case, an injection level in the case where signal B isinserted into signal A may be defined by Equation 1 below:

$\begin{matrix}{{{Injectionlevel}\mspace{14mu} ({dB})} = {{- 10}\; {\log_{10}\left( \frac{{Signal}\mspace{14mu} {power}\mspace{14mu} {of}\mspace{14mu} B}{{Signal}\mspace{14mu} {power}\mspace{14mu} {of}\mspace{14mu} A} \right)}}} & (1)\end{matrix}$

For example, assuming that the injection level is 3 dB when the enhancedlayer signal is inserted into the core layer signal, Equation 1 meansthat the enhanced layer signal has power corresponding to half of thepower of the core layer signal.

In this case, the injection level controller 330 may adjust the powerlevel of the enhanced layer signal from 0 dB to 25.0 dB in steps of 0.5dB or 1 dB.

In general, transmission power that is assigned to the core layer ishigher than transmission power that is assigned to the enhanced layer,which enables the receiver to decode core layer data first.

In this case, the combiner 340 may be viewed as generating a multiplexedsignal by combining the core layer signal with the power-reducedenhanced layer signal.

The signal obtained by the combination of the combiner 340 is providedto the power normalizer 345 so that the power of the signal can bereduced by a power level corresponding to an increase in power caused bythe combination of the core layer signal and the enhanced layer signal,and then power adjustment is performed. That is, the power normalizer345 reduces the power of the signal, obtained by the multiplexing of thecombiner 340, to a power level corresponding to the core layer signal.Since the level of the combined signal is higher than the level of onelayer signal, the power normalizing of the power normalizer 345 isrequired in order to prevent amplitude clipping, etc. in the remainingportion of a broadcast signal transmission/reception system.

In this case, the power normalizer 345 may adjust the magnitude of thecombined signal to an appropriate value by multiplying the magnitude ofthe combined signal by the normalizing factor of Equation 2 below.Injection level information used to calculate Equation 2 below may betransferred to the power normalizer 345 via a signaling flow:

Normalizing factor=(√{square root over((1+10^(−Injection level (dB)/10)))})⁻¹  (2)

Assuming that the power levels of the core layer signal and the enhancedlayer signal are normalized to 1 when an enhanced layer signal S_(E) isinjected into a core layer signal S_(C) at a preset injection level, acombined signal may be expressed by S_(C)+αS_(E).

In this case, α is scaling factors corresponding to various injectionlevels. That is, the injection level controller 330 may correspond tothe scaling factor.

For example, when the injection level of an enhanced layer is 3 dB, acombined signal may be expressed by

$S_{C} + {\sqrt{\frac{1}{2}}{S_{E}.}}$

Since the power of a combined signal (a multiplexed signal) increasescompared to a core layer signal, the power normalizer 345 needs tomitigate the increase in power.

The output of the power normalizer 345 may be expressed byβ(S_(C)+αS_(E)).

In this case, β is normalizing factors based on various injection levelsof the enhanced layer.

When the injection level of the enhanced layer is 3 dB, the power of thecombined signal is increased by 50% compared to that of the core layersignal. Accordingly, the output of the power normalizer 345 may beexpressed by

${\sqrt{\frac{2}{3}}\left( {S_{C} + {\sqrt{\frac{1}{2}}S_{E}}} \right)}.$

Table 1 below lists scaling factors α and normalizing factors β forvarious injection levels (CL: Core Layer, EL: Enhanced Layer). Therelationships among the injection level, the scaling factor α and thenormalizing factor β may be defined by Equation 3 below:

$\begin{matrix}\left\{ \begin{matrix}{\alpha = 10^{(\frac{{- {Injection}}\mspace{14mu} {level}}{20})}} \\{\beta = \frac{1}{\sqrt{1 + \alpha^{2}}}}\end{matrix} \right. & (3)\end{matrix}$

TABLE 1 EL Injection level relative Scaling Normalizing to CL factor αfactor β  3.0 dB 0.7079458 0.8161736  3.5 dB 0.6683439 0.8314061  4.0 dB0.6309573 0.8457262  4.5 dB 0.5956621 0.8591327  5.0 dB 0.56234130.8716346  5.5 dB 0.5308844 0.8832495  6.0 dB 0.5011872 0.8940022  6.5dB 0.4731513 0.9039241  7.0 dB 0.4466836 0.9130512  7.5 dB 0.42169650.9214231  8.0 dB 0.3981072 0.9290819  8.5 dB 0.3758374 0.9360712  9.0dB 0.3548134 0.9424353  9.5 dB 0.3349654 0.9482180 10.0 dB 0.31622780.9534626

According to the embodiments, the injection level may be a value from 0dB to 25 dB. In case that the injection level is 0 dB, the core layersignal and the enhanced layer signal may be combined at the same power.In this case, the scaling factor may be 1, and the normalizing factormay be 0.7071068.

That is, the power normalizer 345 corresponds to the normalizing factor,and reduces the power of the multiplexed signal by a level by which thecombiner 340 has increased the power.

In this case, each of the normalizing factor and the scaling factor maybe a rational number that is larger than 0 and smaller than 1.

In this case, the scaling factor may decrease as a reduction in powercorresponding to the injection level controller 330 becomes larger, andthe normalizing factor may increase as a reduction in powercorresponding to the injection level controller 330 becomes larger.

The power normalized signal passes through the time interleaver 350 fordistributing burst errors occurring over a channel.

In this case, the time interleaver 350 may be viewed as performinginterleaving that is applied to both the core layer signal and theenhanced layer signal. That is, the core layer and the enhanced layershare the time interleaver, thereby preventing the unnecessary use ofmemory and also reducing latency at the receiver.

Although will be described later in greater detail, the enhanced layersignal may correspond to enhanced layer data restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal. The combiner 340 may combine oneor more extension layer signals having power levels lower than those ofthe core layer signal and the enhanced layer signal with the core layersignal and the enhanced layer signal.

Meanwhile, L1 signaling information including injection levelinformation is encoded by the signaling generation unit 360 includingsignaling-dedicated BICM. In this case, the signaling generation unit360 may receive injection level information IL INFO from the injectionlevel controller 330, and may generate an L1 signaling signal.

In L1 signaling, L1 refers to Layer-1 in the lowest layer of the ISO 7layer model. In this case, the L1 signaling may be included in apreamble.

In general, the L1 signaling may include an FFT size, a guard intervalsize, etc., i.e., the important parameters of the OFDM transmitter, achannel code rate, modulation information, etc., i.e., BICM importantparameters. This L1 signaling signal is combined with data signal into abroadcast signal frame.

The frame builder 370 generates a broadcast signal frame by combiningthe L1 signaling signal with a data signal. In this case, the framebuilder 370 may generate the broadcast signal frame including a preamblefor signaling size information of Physical Layer Pipes (PLPs) and timeinterleaver information shared by the core layer signal and the enhancedlayer signal, using the time interleaved signal. In this case, thebroadcast signal frame may further include a bootstrap.

In this case, the frame builder 370 may generate the broadcast signalframe including a preamble for signaling start position information andsize information for each of Physical Layer Pipes (PLPs). In this case,the Physical Layer Pipes (PLPs) include a core layer physical layer pipecorresponding to the core layer signal and an enhanced layer physicallayer pipe corresponding to the enhanced layer signal. In this case,injection level information corresponding to the enhanced layer signalmay be signaled corresponding to the enhanced layer physical layer pipe.

That is, the injection level information may not be signaled for thecore layer physical layer pipe, and may be signaled only for theenhanced layer physical layer pipe.

In this case, the Physical Layer Pipes (PLPs) may include two or moreenhanced layer physical layer pipes and the two or more enhanced layerphysical layer pipes may have the same injection level information(L1D_plp_ldm_injection_level), when the core layer physical layer pipeis layered division multiplexed with the two or more enhanced layerphysical layer pipes.

In this case, the injection level information may correspond to a valueat least 3 dB larger than a required SNR value corresponding to the corelayer signal before the LDM combining as explained by Equation 10.

In this case, the Physical Layer Pipes may be multiplexed by FrequencyDivision Multiplexing (FDM), and signaling information corresponding tothe Frequency Division Multiplexing may be signaled only with respect tothe core layer physical layer pipes and may not be signaled with respectto the enhanced layer physical layer pipes.

In this case, the signaling information corresponding to the FrequencyDivision Multiplexing may include at least one of physical layer pipetype information (L1D_plp_type), physical layer pipe subslice intervalinformation (L1D_plp_subslice_interval) and physical layer pipe subslicenumber information (L1D_plp_num_subslices).

In this case, the enhanced layer physical layer pipe may follow a cellwriting order corresponding to the signaling information correspondingto the Frequency Division Multiplexing of the core layer physical layerpipe to which the enhanced layer physical layer pipe is layered divisionmultiplexed when the Frequency Division Multiplexing is performed.

In this case, the enhanced layer physical layer pipes which areFrequency Division Multiplexed may have a total size not exceeding 2²⁰cells.

Further, the Physical Layer Pipes may include two or more core layerphysical layer pipes and a time interleaving mode corresponding to thetime interleaver may be one of hybrid time interleaving mode or no timeinterleaving mode, when the enhanced layer physical layer pipe islayered division multiplexed to the two or more core layer physicallayer pipes.

In this case, the two or more core layer physical layer pipes may haveinteger numbers of FEC blocks when the no time interleaving mode isused.

In this case, the two or more core layer physical layer pipes may havethe same time interleaving block size or time interleaving block sizes(the differences between the time interleaving block sizes are less thana predetermined value) when the hybrid time interleaving mode is used.

Further, the Physical Layer Pipes may have the start positioninformation and the size information which are set not to have anyduration where the layered division multiplexing is not applied in thecore layer physical layer pipe which is layered division multiplexedwith the enhanced layer physical layer pipe.

In this case, the core layer physical layer pipe may be modulated by anyone of QPSK, 16 QAM and/or 64 QAM, and may be encoded by a code rate ofup to 7/15 when the 64 QAM is used.

In this case, up to four physical layer pipes may be used for onecomplete delivered product.

In this case, the start position information and the size informationfor the enhanced layer physical layer pipe may be generated using ageneration scheme different from the one for the core layer physicallayer pipe.

In this case, the start position information and the size informationfor the core layer physical layer pipe may be generated based on a firstreference timing, and the start position information and the sizeinformation for the enhanced layer physical layer pipe may be generatedbased on a second reference timing which is different from the firstreference timing.

In this case, the first reference timing may correspond to after thetime-interleaving, and the second reference timing may correspond tobefore the time-interleaving.

In this case, the start position information and the size information ofthe enhanced layer physical layer pipe may be defined with respect tobefore the time-interleaving.

In this case, the start position information and the size information ofthe core layer physical layer pipe may be defined within the currentsubframe.

In this case, the start position information and the size information ofthe core layer physical layer pipe may be defined with respect to afterthe time-interleaving.

In this case, the size information may be set based on the number ofdata cells allocated to each of the Physical Layer Pipes.

In this case, the start position information may be set equal to anindex corresponding to the first data cell of each of the Physical LayerPipes.

In this case, the start position information and the size informationmay be included in the preamble for each of the Physical Layer Pipeswithout checking a condition of a conditional statement corresponding tolayer identification information.

In this case, the frame builder 370 may generate the broadcast signalframe which includes a preamble for signaling a time interleaving modecorresponding to the time interleaver 350.

In this case, the time interleaving mode may be signaled for each of thephysical layer pipes (PLPs).

In this case, the physical layer pipes may include one enhanced layerphysical layer pipe and a plurality of core layer physical layer pipeswhich are layered-division multiplexed with the one enhanced layerphysical layer pipe.

In this case, the time interleaving mode corresponding to the enhancedlayer physical layer pipe may be the same as time interleaving modescorresponding to the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed.

In this case, the time interleaving modes corresponding to the corelayer physical layer pipes with which the enhanced layer physical layerpipe is layered-division multiplexed may be all no time interleavingmode or all hybrid time interleaving mode.

In this case, the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayall use an intra-subframe interleaving mode, when the time interleavingmodes corresponding to the core layer physical layer pipes with whichthe enhanced layer physical layer pipe is layered-division multiplexedare all hybrid time interleaving mode.

In this case, each of core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayconsist of an integer number of FEC blocks within each subframe, whenthe time interleaving modes corresponding to the core layer physicallayer pipes with which the enhanced layer physical layer pipe islayered-division multiplexed are all no time interleaving mode.

In this case, all of available data cells of the subframe may be filledwith dummy modulation values first and then the actual physical layerpipe data may be overwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (x¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

The enhanced layer BICM unit 320, the injection level controller 330,the combiner 340 and the power normalizer 345 may be omitted in case ofa single layer. In this case, the time interleaver 350 may generate thetime-interleaved signal by performing time interleaving on the BICMoutput signal of the core layer BICM unit 310. Moreover, the framebuilder 370 may generate the broadcast signal frame which includes apreamble for signaling a time interleaving mode corresponding to thetime interleaver 350 for each of the physical layer pipes (PLPs).

In this case, the physical layer pipes may include a plurality of corelayer physical layer pipes corresponding to one complete deliveredproduct, and the core layer physical layer pipes may be not layereddivision multiplexed.

In this case, each of the core layer physical layer pipes may use eithera no time interleaving mode or a hybrid time interleaving mode as thetime interleaving mode, and may not use a convolutional interleavingmode.

In this case, all of the core layer physical layer pipes may use anintra-subframe interleaving mode or all of the core layer physical layerpipes may use an inter-subframe interleaving mode, when all of the corelayer physical layer pipes use the hybrid time interleaving mode as thetime interleaving mode.

In this case, all of the core layer physical layer pipes may beconfigured with the same value of L1D_plp_HTI_inter_subframe when all ofthe core layer physical layer pipes use the hybrid time interleavingmode as the time interleaving mode.

In this case, all of the core layer physical layer pipes may use thesame time interleaving unit (N_(IU)) when all of the core layer physicallayer pipes use the hybrid time interleaving mode as the timeinterleaving mode and the inter-subframe interleaving mode.

In this case, any of the core layer physical layer pipes configured withthe hybrid time interleaving mode may use the intra-subframeinterleaving mode when at least one of the core layer physical layerpipes uses the no time interleaving mode as the time interleaving mode.

In this case, the one complete delivered product may correspond to atleast one subframe, and the subframe may be filled with dummy modulationvalues first and then the actual physical layer pipe data may beoverwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the time interleaver 350 may use one of time interleavergroups, a boundary between the time interleaver groups may be a boundarybetween Physical Layer Pipes (PLPs) of a core layer corresponding to thecore layer signal. That is, one of boundaries between Physical LayerPipes (PLPs) of the core layer may be a boundary between the timeinterleaver groups.

In this case, enhanced layer data corresponding to the one of the timeinterleaver groups may include dummy values.

In this case, the dummy values may be inserted after the actual datacells of the last Enhanced PLP in a PLP group so that the total numberof Enhanced Layer cells in the PLP group is the same as the total numberof Core Layer cells in the PLP group.

In this case, the dummy values may be not inserted in core layer data.

In this case, the dummy values may be inserted after core layer andenhanced layer BICMs and before the core layer signal and the enhancedlayer signal are combined.

In this case, the dummy values may correspond to a predeterminedscrambling sequence.

In this case, the scrambling sequence may be modulated by using the sameconstellation mapping that is used for the last Enhanced PLP.

In this case, the dummy values may have the same power as the lastEnhanced PLP.

In this case, the scrambling sequence may be generated by a 16-bit shiftregister corresponding to a predetermined generator polynomial.

In this case, the scrambling sequence may be generated by a generatorpolynomial corresponding to 1+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (X¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

In this case, the time interleaver information may be signaled on thebasis of the core layer.

According to an embodiment, a part of the time interleaver informationmay be signaled on the basis of the core layer, and the other part ofthe time interleaver information may be signaled regardless of thelayers.

That is, the time interleaver information may be signaled based on thelayer identification information corresponding to the core layer.

In this case, the time interleaver 350 may correspond to a hybrid timeinterleaver. In this case, the Physical Layer Pipes (PLPs) of a corelayer and an enhanced layer may include only complete FEC blocks.

In this case, the preamble may be for signaling information foridentifying a part of a FEC block in the enhanced layer in case that theboundary between the time interleaver groups does not correspond to aboundary between FEC blocks in the enhanced layer, the FEC blockcorresponding to the boundary between the time interleaver groups.

In this case, the information for identifying the part of the FEC blockmay include at least one of start position information of a PhysicalLayer Pipe (PLP) in the core layer, start position information of aPhysical Layer Pipe (PLP) in the enhanced layer, modulation informationcorresponding to the enhanced layer, and FEC type informationcorresponding to the enhanced layer.

In this case, the start position information of the Physical Layer Pipe(PLP) may correspond to an index of a first data cell of the PhysicalLayer Pipe (PLP).

In this case, the modulation information may be signaled only if the FECtype information satisfies a predetermined condition.

In this case, the enhanced layer signal may correspond to enhanced layerdata that is restored based on cancellation corresponding to restorationof core layer data corresponding to the core layer signal.

In this case, the time interleaver 350 may correspond to a convolutionaltime interleaver, the time interleaver groups may include the PhysicalLayer Pipe (PLP) which includes an incomplete FEC block, and thepreamble may be for signaling start position information of a firstcomplete FEC block in the Physical Layer Pipe (PLP).

In this case, the time interleaver 350 may perform the interleaving byusing one of a plurality of operation modes.

In this case, the operations modes may include a first mode(L1D_plp_TI_mode=00) corresponding to no time interleaving, a secondmode (L1D_plp_TI_mode=01) for performing a Convolutional timeinterleaving and a third mode (L1D_plp_TI_mode=10) for performing aHybrid time interleaving.

In this case, the preamble may include a field indicating a startposition of a first complete FEC block corresponding to a currentPhysical Layer Pipe for the first mode and the second mode, and may notinclude the field indicating the start position of the first FEC blockfor the third mode.

In this case, the field indicating the start position of the first FECblock may be one of a first field (L1D_plp_fec_block_start) used in thefirst mode (L1D_plp_TI_mode=00) and a second field(L1D_plp_CTI_fec_block_start) used in the second mode(L1D_plp_TI_mode=01), and the first field and the second field may havedifferent lengths. In this case, the first field(L1D_plp_fec_block_start) may indicate a start position of a first FECblock starting in a current Physical Layer Pipe during a currentsubframe and the second field (L1D_plp_CTI_fec_block_start) may indicatea start position of a first complete FEC block of a current PhysicalLayer Pipe leaving a Convolutional time interleaver in current orsubsequent subframes. In this case, both the first field(L1D_plp_fec_block_start) and the second field(L1D_plp_CTI_fec_block_start) may be signaled based on afterinterleaving. In particular, in the case of the second field(L1D_plp_CTI_fec_block_start), the number of bits required for signalingmay increase when the signaling is performed based on afterinterleaving.

In this case, the length of the second field may be longer than thelength of the first field.

In this case, the length of the first field may be determined based on alength of a LDPC codeword and a modulation order and the length of thesecond field may be determined not only by the length of the LDPCcodeword and the modulation order but also by further considering adepth of a Convolutional time interleaver.

In this case, the length of the first field may be 15 bits and thelength of the second field may be 22 bits.

In this case, the first field and the second field may be separatelysignaled for each of a core layer corresponding to the core layer signaland an enhanced layer corresponding to the enhanced layer signal.

In this case, the frame builder 370 may include a bootstrap generatorconfigured to generate the bootstrap, a preamble generator configured togenerate the preamble, and a super-imposed payload generator configuredto generate a super-imposed payload corresponding to thetime-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

The broadcast signal frame may be transmitted via the OFDM transmitterthat is robust to a multi-path and the Doppler phenomenon. In this case,the OFDM transmitter may be viewed as being responsible for thetransmission signal generation of the next generation broadcastingsystem.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be included in thepreamble on the basis of a core layer.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing (IF(j>0))the layer identification information with a predetermined value.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame.

Referring to FIG. 4, a broadcast signal frame includes the bootstrap410, the preamble 420 and the super-imposed payload 430.

The frame shown in FIG. 4, may be included in the super-frame.

In this case, the broadcast signal frame may include at least one ofOFDM symbols. The broadcast signal frame may include a reference symbolor a pilot symbol.

The frame structure in which the Layered Division Multiplexing (LDM) isapplied includes the bootstrap 410, the preamble 420 and thesuper-imposed payload 430 as shown in FIG. 4.

In this case, the bootstrap 410 and the preamble 420 may be seen as thetwo hierarchical preambles.

In this case, the bootstrap 410 may have a shorter length than thepreamble 420 for the fast acquisition and detection. In this case, thebootstrap 410 may have a fixed-length. In this case, the bootstrap mayinclude a fixed-length symbol. For example, the bootstrap 410 mayconsist of four OFDM symbols each of which has 0.5 ms length so that thebootstrap 410 may correspond to the fixed time length of 2 ms.

In this case, the bootstrap 410 may have a fixed bandwidth, and thepreamble 420 and the super-imposed payload 430 may have a variablebandwidth wider than the bootstrap 410.

The preamble 420 may transmit detailed signaling information using arobust LDPC code. In this case, the length of the preamble 420 can bevaried according to the signaling information.

In this case, both the bootstrap 410 and the payload 430 may be seen asa common signal which is shared by a plurality of layers.

The super-imposed payload 430 may correspond to a multiplexed signal ofat least two layer signals. In this case, the super-imposed payload 430may be generated by combining a core layer payload and an enhanced layerpayload at different power levels. In this case, the core layer payloadmay include am in-band signaling section. In this case, the in-bandsignaling section may include signaling information for the enhancedlayer service.

In this case, the bootstrap 410 may include a symbol representing apreamble structure.

In this case, the symbol included in the bootstrap for representing thePreamble structure may be set as shown in the Table 2 below.

TABLE 2 GI Pilot preamble_ FFT Length Pattern structure L1-Basic ModeSize (samples) (DX) 0 L1-Basic Mode 1 8192 2048 3 1 L1-Basic Mode 1 81921536 4 2 L1-Basic Mode 1 8192 1024 3 3 L1-Basic Mode 1 8192 768 4 4L1-Basic Mode 1 16384 4096 3 5 L1-Basic Mode 1 16384 3648 4 6 L1-BasicMode 1 16384 2432 3 7 L1-Basic Mode 1 16384 1536 4 8 L1-Basic Mode 116384 1024 6 9 L1-Basic Mode 1 16384 768 8 10 L1-Basic Mode 1 32768 48643 11 L1-Basic Mode 1 32768 3648 3 12 L1-Basic Mode 1 32768 3648 8 13L1-Basic Mode 1 32768 2432 6 14 L1-Basic Mode 1 32768 1536 8 15 L1-BasicMode 1 32768 1024 12 16 L1-Basic Mode 1 32768 768 16 17 L1-Basic Mode 28192 2048 3 18 L1-Basic Mode 2 8192 1536 4 19 L1-Basic Mode 2 8192 10243 20 L1-Basic Mode 2 8192 768 4 21 L1-Basic Mode 2 16384 4096 3 22L1-Basic Mode 2 16384 3648 4 23 L1-Basic Mode 2 16384 2432 3 24 L1-BasicMode 2 16384 1536 4 25 L1-Basic Mode 2 16384 1024 6 26 L1-Basic Mode 216384 768 8 27 L1-Basic Mode 2 32768 4864 3 28 L1-Basic Mode 2 327683648 3 29 L1-Basic Mode 2 32768 3648 8 30 L1-Basic Mode 2 32768 2432 631 L1-Basic Mode 2 32768 1536 8 32 L1-Basic Mode 2 32768 1024 12 33L1-Basic Mode 2 32768 768 16 34 L1-Basic Mode 3 8192 2048 3 35 L1-BasicMode 3 8192 1536 4 36 L1-Basic Mode 3 8192 1024 3 37 L1-Basic Mode 38192 768 4 38 L1-Basic Mode 3 16384 4096 3 39 L1-Basic Mode 3 16384 36484 40 L1-Basic Mode 3 16384 2432 3 41 L1-Basic Mode 3 16384 1536 4 42L1-Basic Mode 3 16384 1024 6 43 L1-Basic Mode 3 16384 768 8 44 L1-BasicMode 3 32768 4864 3 45 L1-Basic Mode 3 32768 3648 3 46 L1-Basic Mode 332768 3648 8 47 L1-Basic Mode 3 32768 2432 6 48 L1-Basic Mode 3 327681536 8 49 L1-Basic Mode 3 32768 1024 12 50 L1-Basic Mode 3 32768 768 16Si L1-Basic Mode 4 8192 2048 3 52 L1-Basic Mode 4 8192 1536 4 53L1-Basic Mode 4 8192 1024 3 54 L1-Basic Mode 4 8192 768 4 55 L1-BasicMode 4 16384 4096 3 56 L1-Basic Mode 4 16384 3648 4 57 L1-Basic Mode 416384 2432 3 58 L1-Basic Mode 4 16384 1536 4 59 L1-Basic Mode 4 163841024 6 60 L1-Basic Mode 4 16384 768 8 61 L1-Basic Mode 4 32768 4864 3 62L1-Basic Mode 4 32768 3648 3 63 L1-Basic Mode 4 32768 3648 8 64 L1-BasicMode 4 32768 2432 6 65 L1-Basic Mode 4 32768 1536 8 66 L1-Basic Mode 432768 1024 12 67 L1-Basic Mode 4 32768 768 16 68 L1-Basic Mode 5 81922048 3 69 L1-Basic Mode 5 8192 1536 4 70 L1-Basic Mode 5 8192 1024 3 71L1-Basic Mode 5 8192 768 4 72 L1-Basic Mode 5 16384 4096 3 73 L1-BasicMode 5 16384 3648 4 74 L1-Basic Mode 5 16384 2432 3 75 L1-Basic Mode 516384 1536 4 76 L1-Basic Mode 5 16384 1024 6 77 L1-Basic Mode 5 16384768 8 78 L1-Basic Mode 5 32768 4864 3 79 L1-Basic Mode 5 32768 3648 3 80L1-Basic Mode 5 32768 3648 8 81 L1-Basic Mode 5 32768 2432 6 82 L1-BasicMode 5 32768 1536 8 83 L1-Basic Mode 5 32768 1024 12 84 L1-Basic Mode 532768 768 16 85 L1-Basic Mode 6 8192 2048 3 86 L1-Basic Mode 6 8192 15364 87 L1-Basic Mode 6 8192 1024 3 88 L1-Basic Mode 6 8192 768 4 89L1-Basic Mode 6 16384 4096 3 90 L1-Basic Mode 6 16384 3648 4 91 L1-BasicMode 6 16384 2432 3 92 L1-Basic Mode 6 16384 1536 4 93 L1-Basic Mode 616384 1024 6 94 L1-Basic Mode 6 16384 768 8 95 L1-Basic Mode 6 327684864 3 96 L1-Basic Mode 6 32768 3648 3 97 L1-Basic Mode 6 32768 3648 898 L1-Basic Mode 6 32768 2432 6 99 L1-Basic Mode 6 32768 1536 8 100L1-Basic Mode 6 32768 1024 12 101 L1-Basic Mode 6 32768 768 16 102L1-Basic Mode 7 8192 2048 3 103 L1-Basic Mode 7 8192 1536 4 104 L1-BasicMode 7 8192 1024 3 105 L1-Basic Mode 7 8192 768 4 106 L1-Basic Mode 716384 4096 3 107 L1-Basic Mode 7 16384 3648 4 108 L1-Basic Mode 7 163842432 3 109 L1-Basic Mode 7 16384 1536 4 110 L1-Basic Mode 7 16384 1024 6111 L1-Basic Mode 7 16384 768 8 112 L1-Basic Mode 7 32768 4864 3 113L1-Basic Mode 7 32768 3648 3 114 L1-Basic Mode 7 32768 3648 8 115L1-Basic Mode 7 32768 2432 6 116 L1-Basic Mode 7 32768 1536 8 117L1-Basic Mode 7 32768 1024 12 118 L1-Basic Mode 7 32768 768 16 119Reserved Reserved Reserved Reserved 120 Reserved Reserved ReservedReserved 121 Reserved Reserved Reserved Reserved 122 Reserved ReservedReserved Reserved 123 Reserved Reserved Reserved Reserved 124 ReservedReserved Reserved Reserved 125 Reserved Reserved Reserved Reserved 126Reserved Reserved Reserved Reserved 127 Reserved Reserved ReservedReserved

For example, a fixed-length symbol of 7-bit may be assigned forrepresenting the preamble structure shown in the Table 2.

The L1-Basic Mode 1, L1-Basic Mode 2 and L1-Basic Mode 3 in the Table 2may correspond to QPSK and 3/15 LDPC.

The L1 Basic Mode 4 in the Table 2 may correspond to 16-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1 Basic Mode 5 in the Table 2 may correspond to 64-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1-Basic Mode 6 and L1-Basic Mode 7 in the Table 2 may correspond to256-NUC (Non Uniform Constellation) and 3/15 LDPC. Hereafter, themodulation scheme/code rate represents a combination of a modulationscheme and a code rate such as QPSK and 3/15 LDPC.

The FFT size in the Table 2 may represent a size of Fast FourierTransform.

The GI length in the Table 2 may represent the Guard Interval Length,may represent a length of the guard interval which is not data in a timedomain. In this case, the guard interval is longer, the system is morerobust.

The Pilot Pattern in the Table 2 may represent Dx of the pilot pattern.Although it is not shown in the Table 2 explicitly, Dy may be all 1 inthe example of Table 2. For example, Dx=3 may mean that one pilot forchannel estimation is included in x-axis direction in every threesymbols. For example, Dy=1 may mean the pilot is included every time iny-axis direction.

As shown in the Table 2, the preamble structure corresponding to asecond modulation scheme/code rate which is more robust than a firstmodulation scheme/code rate may be allocated in the lookup table priorto the preamble structure corresponding to the first modulationscheme/code rate.

In this case, the being allocated prior to other preamble structure maymean being stored in the lookup table corresponding to a serial numberless than the serial number of the other preamble structure.

Furthermore, the preamble structure corresponding to a second FFT sizewhich is shorter than a first FFT size may be allocated in the lookuptable prior to the preamble structure corresponding to a first FFT sizein case of the same modulation scheme/code rate.

Furthermore, the preamble structure corresponding to a second guardinterval which is longer than a first guard interval may be allocated inthe lookup table prior to the preamble structure corresponding to thefirst guard interval in case of the same modulation scheme/code rate andthe same FFT size.

As shown in the Table 2, the setting of the order in which the preamblestructures are assigned in the lookup table may make the recognition ofthe preamble structure using the bootstrap more efficient.

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4.

Referring to FIG. 5, the bootstrap 510 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 520 using the demodulated information.

The core layer data 530 is demodulated using the signaling informationand the enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data. In this case, thecancellation corresponding to the core layer data will be described indetail later.

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4.

Referring to FIG. 6, the bootstrap 610 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 620 using the demodulated information.

The core layer data 630 is demodulated using the signaling information.In this case, the core layer data 630 includes in-band signaling section650. The in-band signaling section 650 includes signaling informationfor the enhanced layer service. The bandwidth is used more efficientlythrough the in-band signaling section 650. In this case, the in-bandsignaling section 650 may be included in the core layer which is morerobust than the enhanced layer.

The basic signaling information and the information for the core layerservice may be transferred through the preamble 620 and the signalinginformation for the enhanced layer service may be transferred throughthe in-band signaling section 650 in the example of the FIG. 6.

The enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data.

In this case, the signaling information may be L1 (Layer-1) signalinginformation. The L1 signaling information may include information forphysical layer parameters.

Referring to FIG. 4, a broadcast signal frame includes an L1 signalingsignal and a data signal. For example, the broadcast signal frame may bean ATSC 3.0 frame.

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1.

Referring to FIG. 7, it can be seen that an apparatus for generatingbroadcast signal frame multiplexes data corresponding to N (N is anatural number that is equal to or larger than 1) extension layerstogether in addition to core layer data and enhanced layer data.

That is, the apparatus for generating the broadcast signal frame in FIG.7 includes N extension layer BICM units 410, . . . , 430 and injectionlevel controllers 440, . . . , 460 in addition to a core layer BICM unit310, an enhanced layer BICM unit 320, an injection level controller 330,a combiner 340, a power normalizer 345, a time interleaver 350, asignaling generation unit 360, and a frame builder 370.

The core layer BICM unit 310, enhanced layer BICM unit 320, injectionlevel controller 330, combiner 340, power normalizer 345, timeinterleaver 350, signaling generation unit 360 and frame builder 370shown in FIG. 7 have been described in detail with reference to FIG. 3.

Each of the N extension layer BICM units 410, . . . , 430 independentlyperforms BICM encoding, and each of the injection level controllers 440,. . . , 460 performs power reduction corresponding to a correspondingextension layer, thereby enabling a power reduced extension layer signalto be combined with other layer signals via the combiner 340.

In this case, each of the error correction encoders of the extensionlayer BICM units 410, . . . , 430 may be formed by connecting a BCHencoder and an LDPC encoder in series.

In particular, it is preferred that a reduction in power correspondingto each of the injection level controllers 440, . . . , 460 be higherthan the reduction in power of the injection level controller 330. Thatis, a lower one of the injection level controllers 330, 440, . . . , 460shown in FIG. 7 may correspond to a larger reduction in power.

Injection level information provided by the injection level controllers330, 440 and 460 shown in FIG. 7 is included in the broadcast signalframe of the frame builder 370 via the signaling generation unit 360,and is then transmitted to the receiver. That is, the injection level ofeach layer is contained in the L1 signaling information and thentransferred to the receiver.

In the present invention, the adjustment of power may correspond toincreasing or decreasing the power of an input signal, and maycorrespond to increasing or decreasing the gain of an input signal.

The power normalizer 345 mitigates an increase in power caused by thecombination of a plurality of layer signals by means of the combiner340.

In the example shown in FIG. 7, the power normalizer 345 may adjust thepower of a signal to appropriate magnitude by multiplying the magnitudeof a signal, into which the signals of the respective layers arecombined, by a normalizing factor by using Equation 4 below:

$\begin{matrix}{{{Normalizing}\mspace{14mu} {factor}} = \left( \sqrt{\begin{pmatrix}\begin{matrix}{1 + 10^{{- {Injectionlevel}}\mspace{14mu} {\# 1}\mspace{11mu} {{({dB})}/10}} +} \\{10^{{- {Injectionlevel}}\mspace{14mu} {\# 2}\mspace{11mu} {{({dB})}/10}} + \ldots +}\end{matrix} \\10^{{- {Injectionlevel}}\mspace{14mu} \# {({N + 1})}\mspace{11mu} {{({dB})}/10}}\end{pmatrix}} \right)^{- 1}} & (4)\end{matrix}$

The time interleaver 350 performs interleaving equally applied to thesignals of the layers by interleaving the signals combined by thecombiner 340.

FIG. 8 is a block diagram showing still an example of the signaldemultiplexer shown in FIG. 1.

Referring to FIG. 8, a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, core layer BICM decoder 520, an enhanced layersymbol extractor 530, a de-injection level controller 1020, and anenhanced layer BICM decoder 540.

In this case, the signal demultiplexer shown in FIG. 8 may correspond tothe apparatus for generating the broadcast signal frame shown in FIG. 3.

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as time/frequencysynchronization, channel estimation and equalization, and performs anoperation related to the distribution of burst errors occurring over achannel. In this case, the L1 signaling information is decoded by theOFDM receiver first, and is then used for the decoding of data. Inparticular, the injection level information of the L1 signalinginformation may be transferred to the de-normalizer 1010 and thede-injection level controller 1020. In this case, the OFDM receiver maydecode the received signal in the form of a broadcast signal frame, forexample, an ATSC 3.0 frame, may extract the data symbol part of theframe, and may provide the extracted data symbol part to the timedeinterleaver 510. That is, the time deinterleaver 510 distributes bursterrors occurring over a channel by performing deinterleaving whilepassing a data symbol therethrough.

In this case, the time deinterleaver 510 may perform an operationcorresponding to the time interleaver. In this case, the timedeinterleaver 510 may perform the deinterleaving by using one of aplurality of operation modes and may perform the deinterleaving by usingthe time interleaver information signaled related to the operation ofthe time interleaver.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power. That is, the de-normalizer 1010divides the received signal by the normalizing factor of Equation 2.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 8, the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment is performed beforeinterleaving in some embodiments.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In this case, the core layer symbol demapper may calculate an LLR valuefor each bit using a predetermined constellation. In this case, theconstellation used by the core layer symbol mapper may vary depending onthe combination of the code rate and the modulation order that are usedby the transmitter.

In this case, the core layer bit deinterleaver may performdeinterleaving on calculated LLR values on an LDPC code word basis.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen mixed with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been mixed withparity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

Furthermore, the enhanced layer error correction decoder may be formedby connecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

The enhanced layer symbol extractor 530 may receive all bits from thecore layer error correction decoder of the core layer BICM decoder 520,may extract enhanced layer symbols from the output signal of the timedeinterleaver 510 or de-normalizer 1010. In an embodiment, the enhancedlayer symbol extractor 530 may not be provided with all bits by theerror correction decoder of the core layer BICM decoder 520, but may beprovided with LDPC information bits or BCH information bits by the errorcorrection decoder of the core layer BICM decoder 520.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits+parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020. In particular, when LDPC information bits areprovided, the enhanced layer symbol extractor 530 may further include acore layer LDPC encoder. Furthermore, when BCH information bits areprovided, the enhanced layer symbol extractor 530 may further includenot only a core layer LDPC encoder but also a core layer BCH encoder.

In this case, the core layer LDPC encoder, core layer BCH encoder, corelayer bit interleaver and core layer symbol mapper included in theenhanced layer symbol extractor 530 may be the same as the LDPC encoder,BCH encoder, bit interleaver and symbol mapper of the core layerdescribed with reference to FIG. 3.

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540. For example, if at the transmitter, the powerused to combine the enhanced layer signal is lower than the power usedto combine the core layer signal by 3 dB, the de-injection levelcontroller 1020 functions to increase the power of the input signal by 3dB.

In this case, the de-injection level controller 1020 may be viewed asreceiving injection level information from the OFDM receiver andmultiplying an extracted enhanced layer signal by the enhanced layergain of Equation 5:

Enhanced layer gain=(√{square root over(10^(−Injection level (dB)/10))})⁻¹  (5)

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

Although the enhanced layer BICM decoder 540 performs a task similar toa task that is performed by the core layer BICM decoder 520, theenhanced layer LDPC decoder generally performs LDPC decoding related toa code rate equal to or higher than 6/15.

For example, the core layer may use LDPC code having a code rate equalto or higher than 5/15, and the enhanced layer may use LDPC code havinga code rate equal to or higher than 6/15. In this case, in a receptionenvironment in which enhanced layer data can be decoded, core layer datamay be decoded using only a small number of LDPC decoding iterations.Using this characteristic, in the hardware of the receiver, a singleLDPC decoder is shared by the core layer and the enhanced layer, andthus the cost required to implement the hardware can be reduced. In thiscase, the core layer LDPC decoder may use only some time resources (LDPCdecoding iterations), and the enhanced layer LDPC decoder may use mosttime resources.

That is, the signal demultiplexer shown in FIG. 8 restores core layerdata first, leaves only the enhanced layer symbols by cancellation thecore layer symbols in the received signal symbols, and then restoresenhanced layer data by increasing the power of the enhanced layersymbols. As described with reference to FIGS. 3 and 5, signalscorresponding to respective layers are combined at different powerlevels, and thus data restoration having the smallest error can beachieved only if restoration starts with a signal combined with thestrongest power.

Accordingly, in the example shown in FIG. 8, the signal demultiplexermay include the time deinterleaver 510 configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal; a de-normalizer 1010 configured to increase the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; the core layer BICM decoder 520 configured to restore corelayer data from the signal power-adjusted by the de-normalizer 1010; theenhanced layer symbol extractor 530 configured to extract an enhancedlayer signal by performing cancellation, corresponding to the core layerdata, on the signal power-adjusted by the de-normalizer 1010 using theoutput signal of the core layer FEC decoder of the core layer BICMdecoder 520; a de-injection level controller 1020 configured to increasethe power of the enhanced layer signal by a level corresponding to areduction in power by the injection power level controller of thetransmitter; and an enhanced layer BICM decoder 540 configured torestore enhanced layer data using the output signal of the de-injectionlevel controller 1020.

In this case, the enhanced layer symbol extractor may receive all codewords from the core layer LDPC decoder of the core layer BICM decoder,and may immediately perform bit interleaving on the all code words.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and may perform core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer BCH decoder of the core layer BICMdecoder, and may perform core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

In this case, the de-normalizer and the de-injection level controllermay receive injection level information IL INFO provided based on L1signaling, and may perform power control based on the injection levelinformation.

In this case, the core layer BICM decoder may have a bit rate lower thanthat of the enhanced layer BICM decoder, and may be more robust than theenhanced layer BICM decoder.

In this case, the de-normalizer may correspond to the reciprocal of thenormalizing factor.

In this case, the de-injection level controller may correspond to thereciprocal of the scaling factor.

In this case, the enhanced layer data may be restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal.

In this case, the signal demultiplexer further may include one or moreextension layer symbol extractors each configured to extract anextension layer signal by performing cancellation corresponding toprevious layer data; one or more de-injection level controllers eachconfigured to increase the power of the extension layer signal by alevel corresponding to a reduction in power by the injection levelcontroller of the transmitter; and one or more extension layer BICMdecoders configured to restore one or more pieces of extension layerdata using the output signals of the one or more de-injection levelcontrollers.

From the configuration shown in FIG. 8, it can be seen that a signaldemultiplexing method according to an embodiment of the presentinvention includes generating a time-deinterleaved signal by applyingtime deinterleaving to a received signal; increasing the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; restoring core layer data from the power-adjusted signal;extracting an enhanced layer signal by performing cancellation,corresponding to the core layer data, on the power-adjusted signal;increasing the power of the enhanced layer signal by a levelcorresponding to a reduction in power by the injection power levelcontroller of the transmitter; and restoring enhanced layer data usingthe enhanced layer data.

In this case, extracting the enhanced layer signal may include receivingall code words from the core layer LDPC decoder of the core layer BICMdecoder, and immediately performing bit interleaving on the all codewords.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and performing core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer BCH decoder of the core layer BICMdecoder, and performing core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder 520 and the enhanced layer symbol extractor 530 shown in FIG. 8.

Referring to FIG. 9, the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 9, the core layer error correctiondecoder includes the core layer LDPC decoder and the core layer BCHdecoder.

Furthermore, in the example shown in FIG. 9, the core layer LDPC decoderprovides all code words, including parity bits, to the enhanced layersymbol extractor 530. That is, although the LDPC decoder generallyoutputs only the information bits of all the LDPC code words, the LDPCdecoder may output all the code words.

In this case, although the enhanced layer symbol extractor 530 may beeasily implemented because it does not need to include a core layer LDPCencoder or a core layer BCH encoder, there is a possibility that aresidual error may remain in the LDPC code parity part.

FIG. 10 is a block diagram showing another example of the core layerBICM decoder 520 and the enhanced layer symbol extractor 530 shown inFIG. 8.

Referring to FIG. 10, the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 10, the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

Furthermore, in the example shown in FIG. 10, the core layer LDPCdecoder provides information bits, excluding parity bits, to theenhanced layer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 does notneed to include a core layer BCH encoder, it must include a core layerLDPC encoder.

A residual error that may remain in the LDPC code parity part may beeliminated more desirably in the example shown in FIG. 10 than in theexample shown in FIG. 9.

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder 520 and the enhanced layer symbol extractor 530 shownin FIG. 8.

Referring to FIG. 11, the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 11, the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

In the example shown in FIG. 11, the output of the core layer BCHdecoder corresponding to core layer data is provided to the enhancedlayer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 has highcomplexity because it must include both a core layer LDPC encoder and acore layer BCH encoder, it guarantees higher performance than those inthe examples of FIGS. 9 and 10.

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1.

Referring to FIG. 12, a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, a core layer BICM decoder 520, an enhanced layersymbol extractor 530, an enhanced layer BICM decoder 540, one or moreextension layer symbol extractors 650 and 670, one or more extensionlayer BICM decoders 660 and 680, and de-injection level controllers1020, 1150 and 1170.

In this case, the signal demultiplexer shown in FIG. 12 may correspondto the apparatus for generating broadcast signal frame shown in FIG. 7.

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as synchronization, channelestimation and equalization, and performs an operation related to thedistribution of burst errors occurring over a channel. In this case, L1signaling information may be decoded by the OFDM receiver first, andthen may be used for data decoding. In particular, the injection levelinformation of the L1 signaling information may be transferred to thede-normalizer 1010 and the de-injection level controllers 1020, 1150 and1170.

In this case, the de-normalizer 1010 may obtain the injection levelinformation of all layers, may obtain a de-normalizing factor usingEquation 6 below, and may multiply the input signal with thede-normalizing factor:

$\begin{matrix}{{{De}\text{-}{normalizing}\mspace{14mu} {factor}} = {\left( {{normalizing}\mspace{20mu} {factor}} \right)^{- 1} = \left( \sqrt{\begin{pmatrix}\begin{matrix}{1 + 10^{{- {Injectionlevel}}\mspace{14mu} {\# 1}\mspace{11mu} {{({dB})}/10}} +} \\{10^{{- {Injectionlevel}}\mspace{14mu} {\# 2}\mspace{11mu} {{({dB})}/10}} + \ldots +}\end{matrix} \\10^{{- {Injectionlevel}}\mspace{14mu} \# {({N + 1})}\mspace{11mu} {{({dB})}/10}}\end{pmatrix}} \right)}} & (6)\end{matrix}$

That is, the de-normalizing factor is the reciprocal of the normalizingfactor expressed by Equation 4 above.

In an embodiment, when the N1 signaling includes not only injectionlevel information but also normalizing factor information, thede-normalizer 1010 may simply obtain a de-normalizing factor by takingthe reciprocal of a normalizing factor without the need to calculate thede-normalizing factor using an injection level.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 12, the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment can be performed beforeinterleaving in an embodiment.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen combined with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been combinedwith parity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

The enhanced layer error correction decoder may be also formed byconnecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

Moreover, the extension layer error correction decoder may be alsoformed by connecting an extension layer LDPC decoder and an extensionlayer BCH decoder in series. That is, the input of the extension layererror correction decoder may be input to the extension layer LDPCdecoder, the output of the extension layer LDPC decoder may be input tothe extension layer BCH decoder, and the output of the extension layerBCH decoder may become the output of the extension layer errorcorrection decoder.

In particular, the tradeoff between the complexity of implementation,regarding which of the outputs of the error correction decoders will beused, which has been described with reference to FIGS. 9, 10 and 11, andperformance is applied to not only the core layer BICM decoder 520 andenhanced layer symbol extractor 530 of FIG. 12 but also the extensionlayer symbol extractors 650 and 670 and the extension layer BICMdecoders 660 and 680.

The enhanced layer symbol extractor 530 may receive the all bits fromthe core layer BICM decoder 520 of the core layer error correctiondecoder, and may extract enhanced layer symbols from the output signalof the time deinterleaver 510 or the denormalizer 1010. In anembodiment, the enhanced layer symbol extractor 530 may not receive allbits from the error correction decoder of the core layer BICM decoder520, but may receive LDPC information bits or BCH information bits.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits+parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020.

In this case, the core layer bit interleaver and core layer symbolmapper included in the enhanced layer symbol extractor 530 may be thesame as the core layer bit interleaver and the core layer symbol mappershown in FIG. 7.

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540.

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

In particular, the enhanced layer error correction decoder may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the enhanced layererror correction decoder may output only information bits as enhancedlayer data, and may output all bits in which information bits have beenmixed with parity bits to the extension layer symbol extractor 650.

The extension layer symbol extractor 650 receives all bits from theenhanced layer error correction decoder of the enhanced layer BICMdecoder 540, and extracts extension layer symbols from the output signalof the de-injection level controller 1020.

In this case, the de-injection level controller 1020 may amplify thepower of the output signal of the subtracter of the enhanced layersymbol extractor 530.

In this case, the extension layer symbol extractor 650 includes abuffer, a subtracter, an enhanced layer symbol mapper, and an enhancedlayer bit interleaver. The buffer stores the output signal of thede-injection level controller 1020. The enhanced layer bit interleaverreceives the all bits information (bits+parity bits) of the enhancedlayer BICM decoder, and performs enhanced layer bit interleaving that isthe same as that of the transmitter. The enhanced layer symbol mappergenerates enhanced layer symbols, which are the same as those of thetransmitter, from the interleaved signal. The subtracter obtainsextension layer symbols by subtracting the output signal of the enhancedlayer symbol mapper from the signal stored in the buffer, and transfersthe extension layer symbols to the extension layer BICM decoder 660.

In this case, the enhanced layer bit interleaver and the enhanced layersymbol mapper included in the extension layer symbol extractor 650 maybe the same as the enhanced layer bit interleaver and the enhanced layersymbol mapper shown in FIG. 7.

The de-injection level controller 1150 increases power by a level bywhich the injection level controller of a corresponding layer hasdecreased the power at the transmitter.

In this case, the de-injection level controller may be viewed asperforming the operation of multiplying the extension layer gain ofEquation 7 below. In this case, a 0-th injection level may be consideredto be 0 dB:

$\begin{matrix}{{n\text{-}{th}\mspace{11mu} {extensionlayer}\mspace{14mu} {gain}} = \frac{10^{{- {Injectionlevel}}\mspace{14mu} \# {({n - 1})}\mspace{11mu} {{({dB})}/10}}}{10^{{- {Injectionlevel}}\mspace{14mu} \# {{n{({dB})}}/10}}}} & (7)\end{matrix}$

The extension layer BICM decoder 660 receives the extension layersymbols whose power has been increased by the de-injection levelcontroller 1150, and restores extension layer data.

In this case, the extension layer BICM decoder 660 may include anextension layer symbol demapper, an extension layer bit deinterleaver,and an extension layer error correction decoder. The extension layersymbol demapper calculates LLR values related to the extension layersymbols, the extension layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the extension layer errorcorrection decoder corrects error occurring over a channel.

In particular, each of the extension layer symbol extractor and theextension layer BICM decoder may include two or more extractors ordecoders if two or more extension layers are present.

That is, in the example shown in FIG. 12, the extension layer errorcorrection decoder of the extension layer BICM decoder 660 may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the extension layererror correction decoder outputs only information bits as extensionlayer data, and may output all bits in which information bits have beenmixed with parity bits to the subsequent extension layer symbolextractor 670.

The configuration and operation of the extension layer symbol extractor670, the extension layer BICM decoder 680 and the de-injection levelcontroller 1170 can be easily understood from the configuration andoperation of the above-described extension layer symbol extractor 650,extension layer BICM decoder 660 and de-injection level controller 1150.

A lower one of the de-injection level controllers 1020, 1150 and 1170shown in FIG. 12 may correspond to a larger increase in power. That is,the de-injection level controller 1150 may increase power more than thede-injection level controller 1020, and the de-injection levelcontroller 1170 may increase power more than the de-injection levelcontroller 1150.

It can be seen that the signal demultiplexer shown in FIG. 12 restorescore layer data first, restores enhanced layer data using thecancellation of core layer symbols, and restores extension layer datausing the cancellation of enhanced layer symbols. Two or more extensionlayers may be provided, in which case restoration starts with anextension layer combined at a higher power level.

FIG. 13 is a diagram showing in an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal.

Referring to FIG. 13, it can be seen that when a multiplexed signal isgenerated by combining a core layer signal with an enhanced layer signalwhose power has been reduced by an injection level, the power level ofthe multiplexed signal is higher than the power level of the core layersignal or the enhanced layer signal.

In this case, the injection level that is adjusted by the injectionlevel controllers shown in FIGS. 3 and 7 may be adjusted from 0 dB to25.0 dB in steps of 0.5 dB or 1 dB. When the injection level is 3.0 dB,the power of the enhanced layer signal is lower than that of the corelayer signal by 3 dB. When the injection level is 10.0 dB, the power ofthe enhanced layer signal is lower than that of the core layer signal by10 dB. This relationship may be applied not only between a core layersignal and an enhanced layer signal but also between an enhanced layersignal and an extension layer signal or between extension layer signals.

The power normalizers shown in FIGS. 3 and 7 may adjust the power levelafter the combination, thereby solving problems, such as the distortionof the signal, that may be caused by an increase in power attributableto the combination.

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention.

Referring to FIG. 14, in the method according to the embodiment of thepresent invention, BICM is applied to core layer data at step S1210.

Furthermore, in the method according to the embodiment of the presentinvention, BICM is applied to enhanced layer data at step S1220.

The BICM applied at step S1220 may be different from the BICM applied tostep S1210. In this case, the BICM applied at step S1220 may be lessrobust than the BICM applied to step S1210. In this case, the bit rateof the BICM applied at step S1220 may be less robust than that of theBICM applied to step S1210.

In this case, an enhanced layer signal may correspond to the enhancedlayer data that is restored based on cancellation corresponding to therestoration of the core layer data corresponding to a core layer signal.

Furthermore, in the method according to the embodiment of the presentinvention, a power-reduced enhanced layer signal is generated byreducing the power of the enhanced layer signal at step S1230.

In this case, at step S1230, an injection level may be changed from 00dB to 25.0 dB in steps of 0.5 dB or 1 dB.

Furthermore, in the method according to the embodiment of the presentinvention, a multiplexed signal is generated by combining the core layersignal and the power-reduced enhanced layer signal at step S1240.

In this case, at step S1240, the core layer signal and the enhancedlayer signal may be combined at different power levels so that the powerlevel of the enhanced layer signal is lower than the power level of thecore layer signal.

In this case, at step S1240, one or more extension layer signals havinglower power levels than the core layer signal and the enhanced layersignal may be combined with the core layer signal and the enhanced layersignal.

Furthermore, in the method according to the embodiment of the presentinvention, the power-normalizing for reducing the power of themultiplexed signal is performed at step S1250.

In this case, at step S1250, the power of the multiplexed signal may bereduced to the power of the core layer signal. In this case, at stepS1250, the power of the multiplexed signal may be reduced by a level bywhich the power has been increased at step S1240.

Furthermore, in the method according to the embodiment of the presentinvention, a time-interleaved signal is generated by performing timeinterleaving at step S1260.

In this case, at step S1260, the time interleaved signal may begenerated by performing time-interleaving that is applied to both thecore layer signal and the enhanced layer signal.

According to an embodiment, the time-interleaved signal may be generatedby performing time interleaving on the BICM output signal in case of asingle layer at step S1260.

In this case, the step S1260 may use one of time interleaver groups, anda boundary between the time interleaver groups may be a boundary betweenPhysical Layer Pipes (PLPs) of a core layer corresponding to the corelayer signal.

In this case, the step S1260 may use a hybrid time interleaver forperforming the interleaving. In this case, Physical Layer Pipes (PLPs)of a core layer and an enhanced layer may include only complete FECblocks.

In this case, the step S1260 may use a convolutional time interleaverfor performing the interleaving, the time interleaver groups may includethe Physical Layer Pipe (PLP) which includes an incomplete FEC block,and the preamble may be for signaling start position information of afirst complete FEC block in the Physical Layer Pipe (PLP).

In this case, the step S1260 may be performed by using one of aplurality of operation modes.

In this case, the operation modes may include a first mode correspondingto no time interleaving, a second mode for performing a Convolutionaltime interleaving and a third mode for performing a Hybrid timeinterleaving.

In this case, the operation mode may correspond to the time interleavingmode. In this case, the time interleaving mode corresponding to the timeinterleaving may be signaled for each physical layer pipe. In this case,the time interleaving mode may be included in the preamble.

Furthermore, in the method according to the embodiment of the presentinvention, a broadcast signal frame including a preamble for signalingthe time interleaving mode corresponding to the time interleaving foreach of the physical layer pipes (PLPs) is generated at step S1270.

In this case, the step S1270 may generate the broadcast signal frameincluding a preamble for signaling start position information and sizeinformation for each of Physical Layer Pipes (PLPs). In this case, thephysical layer pipes may include a core layer physical layer pipecorresponding to the core layer signal and an enhanced layer physicallayer pipe corresponding to the enhanced layer signal.

In this case, injection level information corresponding to the enhancedlayer signal may be signaled corresponding to the enhanced layerphysical layer pipe.

In this case, the Physical Layer Pipes (PLPs) may include two or moreenhanced layer physical layer pipes and the two or more enhanced layerphysical layer pipes may have the same injection level information(L1D_plp_ldm_injection_level), when the core layer physical layer pipeis layered division multiplexed with the two or more enhanced layerphysical layer pipes.

In this case, the injection level information may correspond to a valueat least 3 dB larger than a required SNR value corresponding to the corelayer signal before the LDM combining as explained by Equation 10.

In this case, the Physical Layer Pipes may be multiplexed by FrequencyDivision Multiplexing (FDM), and signaling information corresponding tothe Frequency Division Multiplexing may be signaled only with respect tothe core layer physical layer pipes and may not be signaled with respectto the enhanced layer physical layer pipes.

In this case, the signaling information corresponding to the FrequencyDivision Multiplexing may include at least one of physical layer pipetype information (L1D_plp_type), physical layer pipe subslice intervalinformation (L1D_plp_subslice_interval) and physical layer pipe subslicenumber information (L1D_plp_num_subslices).

In this case, the enhanced layer physical layer pipe may follow a cellwriting order corresponding to the signaling information correspondingto the Frequency Division Multiplexing of the core layer physical layerpipe to which the enhanced layer physical layer pipe is layered divisionmultiplexed when the Frequency Division Multiplexing is performed.

In this case, the enhanced layer physical layer pipes which areFrequency Division Multiplexed may have a total size not exceeding 2²⁰cells.

Further, the Physical Layer Pipes may include two or more core layerphysical layer pipes and a time interleaving mode corresponding to thetime interleaver may be one of hybrid time interleaving mode or no timeinterleaving mode, when the enhanced layer physical layer pipe islayered division multiplexed to the two or more core layer physicallayer pipes.

In this case, the two or more core layer physical layer pipes may haveinteger numbers of FEC blocks when the no time interleaving mode isused.

In this case, the two or more core layer physical layer pipes may havethe same time interleaving block size or time interleaving block sizes(the differences between the time interleaving block sizes are less thana predetermined value) when the hybrid time interleaving mode is used.

Further, the Physical Layer Pipes may have the start positioninformation and the size information which are set not to have anyduration where the layered division multiplexing is not applied in thecore layer physical layer pipe which is layered division multiplexedwith the enhanced layer physical layer pipe.

In this case, the core layer physical layer pipe may be modulated by anyone of QPSK, 16 QAM and/or 64 QAM, and may be encoded by a code rate ofup to 7/15 when the 64 QAM is used.

In this case, up to four physical layer pipes may be used for onecomplete delivered product.

In this case, the start position information and the size informationfor the enhanced layer physical layer pipe may be generated using ageneration scheme different from the one for the core layer physicallayer pipe.

In this case, the start position information and the size informationfor the core layer physical layer pipe may be generated based on a firstreference timing, and the start position information and the sizeinformation for the enhanced layer physical layer pipe may be generatedbased on a second reference timing which is different from the firstreference timing.

In this case, the first reference timing may correspond to after thetime-interleaving, and the second reference timing may correspond tobefore the time-interleaving.

In this case, the start position information and the size information ofthe enhanced layer physical layer pipe may be defined with respect tobefore the time-interleaving.

In this case, the start position information and the size information ofthe core layer physical layer pipe may be defined within the currentsubframe.

In this case, the start position information and the size information ofthe core layer physical layer pipe may be defined with respect to afterthe time-interleaving.

In this case, the physical layer pipes may include a plurality of corelayer physical layer pipes corresponding to one complete deliveredproduct, and the core layer physical layer pipes may be not layereddivision multiplexed.

In this case, each of the core layer physical layer pipes may use eithera no time interleaving mode or a hybrid time interleaving mode as thetime interleaving mode, and may not use a convolutional interleavingmode.

In this case, all of the core layer physical layer pipes may use anintra-subframe interleaving mode or all of the core layer physical layerpipes may use an inter-subframe interleaving mode, when all of the corelayer physical layer pipes use the hybrid time interleaving mode as thetime interleaving mode.

In this case, all of the core layer physical layer pipes may beconfigured with the same value of L1D_plp_HTI_inter_subframe when all ofthe core layer physical layer pipes use the hybrid time interleavingmode as the time interleaving mode.

In this case, all of the core layer physical layer pipes may use thesame time interleaving unit (NO when all of the core layer physicallayer pipes use the hybrid time interleaving mode as the timeinterleaving mode and the inter-subframe interleaving mode.

In this case, any of the core layer physical layer pipes configured withthe hybrid time interleaving mode may use the intra-subframeinterleaving mode when at least one of the core layer physical layerpipes uses the no time interleaving mode as the time interleaving mode.

In this case, the one complete delivered product may correspond to atleast one subframe, and the subframe may be filled with dummy modulationvalues first and then the actual physical layer pipe data may beoverwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the physical layer pipes may include one enhanced layerphysical layer pipe and a plurality of core layer physical layer pipeswhich are layered-division multiplexed with the one enhanced layerphysical layer pipe.

In this case, the time interleaving mode corresponding to the enhancedlayer physical layer pipe may be the same as time interleaving modescorresponding to the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed.

In this case, the time interleaving modes corresponding to the corelayer physical layer pipes with which the enhanced layer physical layerpipe is layered-division multiplexed may be all no time interleavingmode or all hybrid time interleaving mode.

In this case, the core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayall use an intra-subframe interleaving mode, when the time interleavingmodes corresponding to the core layer physical layer pipes with whichthe enhanced layer physical layer pipe is layered-division multiplexedare all hybrid time interleaving mode.

In this case, each of core layer physical layer pipes with which theenhanced layer physical layer pipe is layered-division multiplexed mayconsist of an integer number of FEC blocks within each subframe, whenthe time interleaving modes corresponding to the core layer physicallayer pipes with which the enhanced layer physical layer pipe islayered-division multiplexed are all no time interleaving mode.

In this case, all of available data cells of the subframe may be filledwith dummy modulation values first and then the actual physical layerpipe data may be overwritten for generating the subframe.

In this case, the dummy modulation values may be generated by using ascrambling sequence generated using a generator polynomial correspondingto 1+X+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the dummy modulation values may be generated by mapping avalue of the scrambling sequence into one among two phases which areseparated by 180 degrees.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (x¹³), a fifth bit output (X¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

In this case, the time interleaver information may be signaled on thebasis of the core layer.

In this case, the preamble may be for signaling information foridentifying a part of a FEC block of the enhanced layer in case that theboundary between the time interleaver groups does not correspond to aboundary between FEC blocks of the enhanced layer, the FEC blockcorresponding to the boundary between the time interleaver groups.

In this case, the information for identifying the part of the FEC blockmay include at least one of start position information of a PhysicalLayer Pipe (PLP) in the core layer, start position information of aPhysical Layer Pipe (PLP) in the enhanced layer, modulation informationcorresponding to the enhanced layer, and

FEC type information corresponding to the enhanced layer.

In this case, the start position information of the Physical Layer Pipe(PLP) may correspond to an index of a first data cell of the PhysicalLayer Pipe (PLP).

In this case, the modulation information may be signaled only if the FECtype information satisfies a predetermined condition.

In this case, the enhanced layer signal corresponds to enhanced layerdata that may be restored based on cancellation corresponding torestoration of core layer data corresponding to the core layer signal.

In this case, the step S1270 may include generating the bootstrap;generating the preamble; and generating a super-imposed payloadcorresponding to the time-interleaved signal.

In this case, the preamble may include a PLP identification informationfor identifying Physical Layer Pipes (PLPs); and a layer identificationinformation for identifying layers corresponding to division of layers.

In this case, the PLP identification information and the layeridentification information may be included in the preamble as fieldsdifferent from each other.

In this case, the time interleaver information may be selectivelyincluded in the preamble for each of the Physical Layer Pipes (PLPs)based on a result of comparing (IF(j>0)) the layer identificationinformation with a predetermined value.

In this case, the preamble may selectively include an injection levelinformation corresponding to the injection level controller for each ofthe Physical Layer Pipes (PLPs) based on a result of comparing (IF(j>0))the layer identification information with a predetermined value.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

In this case, the broadcast signal frame may be an ATSC 3.0 frame.

In this case, the L1 signaling information may include injection levelinformation and/or normalizing factor information.

In this case, the preamble may include type information, start positioninformation and size information of the Physical Layer Pipes

In this case, the type information may be for identifying one among afirst type corresponding to a non-dispersed physical layer pipe and asecond type corresponding to a dispersed physical layer pipe.

In this case, the non-dispersed physical layer pipe may be assigned forcontiguous data cell indices, and the dispersed physical layer pipe mayinclude two or more subslices.

In this case, the type information may be selectively signaled accordingto a result of comparing the layer identification information with apredetermined value for each of the Physical Layer Pipes (PLPs).

In this case, the type information may be signaled only for the corelayer.

In this case, the start position information may be identical to anindex corresponding to the first data cell of the physical layer pipe.

In this case, the start position information may indicate the startposition of the physical layer pipe using cell addressing scheme.

In this case, the start position information may be included in thepreamble for each of the Physical Layer Pipes (PLPs) without checking acondition of a conditional statement corresponding to the layeridentification information.

In this case, the size information may be generated based on the numberof data cells assigned to the physical layer pipe.

In this case, the size information may be included in the preamble foreach of the Physical Layer Pipes (PLPs) without checking a condition ofa conditional statement corresponding to the layer identificationinformation.

In this case, the preamble may include a field indicating a startposition of a first complete FEC block corresponding to a currentPhysical Layer Pipe for the first mode and the second mode, and may notinclude the field indicating the start position of the first FEC blockfor the third mode.

In this case, the field indicating the start position of the first FECblock may be one of a first field used in the first mode and a secondfield used in the second mode, and the first field and the second fieldmay have different lengths.

In this case, the length of the second field may be longer than thelength of the first field.

In this case, the length of the first field may be determined based on alength of a LDPC codeword and a modulation order and the length of thesecond field may be determined not only by the length of the LDPCcodeword and the modulation order but also by further considering adepth of a Convolutional time interleaver.

In this case, the length of the first field may be 15 bits and thelength of the second field may be 22 bits.

In this case, the first field and the second field may be separatelysignaled for each of a core layer corresponding to the core layer signaland an enhanced layer corresponding to the enhanced layer signal.

Although not explicitly shown in FIG. 14, the method may further includethe step of generating signaling information including injection levelinformation corresponding to step S1230. In this case, the signalinginformation may be L1 signaling information.

The method of generating broadcast signal frame shown in FIG. 14 maycorrespond to step S210 shown in FIG. 2.

Although not explicitly shown in FIG. 14, the method may further includethe step of inserting dummy values to the enhanced layer data betweenstep S1220 and step S1230.

In this case, the dummy values may be inserted after the actual datacells of the last Enhanced PLP in a PLP group so that the total numberof Enhanced Layer cells in the PLP group is the same as the total numberof Core Layer cells in the PLP group.

In this case, the dummy values may be not inserted in core layer data.

In this case, the dummy values may be inserted after core layer andenhanced layer BICMs and before the core layer signal and the enhancedlayer signal are combined.

In this case, the dummy values may correspond to a predeterminedscrambling sequence.

In this case, the scrambling sequence may be modulated by using the sameconstellation mapping that is used for the last Enhanced PLP.

In this case, the dummy values may have the same power as the lastEnhanced PLP.

In this case, the scrambling sequence may be generated by a 16-bit shiftregister corresponding to a predetermined generator polynomial.

In this case, the scrambling sequence may be generated by a generatorpolynomial corresponding to 1+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

In this case, the scrambling sequence may be generated by using eightbits which are generated by a third bit output (x¹⁴), a fourth bitoutput (X¹³), a fifth bit output (x¹²), a sixth bit output (x¹¹), atenth bit output (x⁷), thirteenth bit output (x⁴), fourteenth bit output(x³) and a sixteenth bit output (x) of a shift register initialized by0xF180 value.

FIG. 15 is a diagram showing a structure of a super-frame which includesbroadcast signal frames according to an embodiment of the presentinvention.

Referring to FIG. 15, the super-frame based on the Layered DivisionMultiplexing (LDM) configures at least one of frame, and each frameconfigures at least one of OFDM symbol.

In this case, each OFDM symbol may start with at least one preamblesymbol. Moreover, the frame may include a reference symbol or a pilotsymbol.

The super-frame 1510 illustrated in FIG. 15, may include a LDM frame1520, a single layer frame without LDM 1530 and a Future Extension Frame(FEF) for future extensibility 1540 and may be configured using TimeDivision Multiplexing (TDM).

The LDM frame 1520 may include an Upper Layer (UL) 1553 and a LowerLayer (LL) 1555 when two layers are applied.

In this case, the upper layer 1553 may correspond to the core layer andthe lower layer 1555 may correspond to the enhanced layer.

In this case, the LDM frame 1520 which includes the upper layer 1553 andthe lower layer 1555 may a bootstrap 1552 and a preamble 1551.

In this case, the upper layer data and the lower layer data may sharethe time interleaver for reducing complexity and memory size and may usethe same frame length and FFT size.

Moreover, the single-layer frame 1530 may include the bootstrap 1562 andthe preamble 1561.

In this case, the single-layer frame 1530 may use a FFT size, timeinterleaver and frame length different from the LDM frame 1520. In thiscase, the single-layer frame 1530 may be multiplexed with the LDM frame1520 in the super-frame 1510 based on TDM scheme.

FIG. 16 is a diagram showing an example of a LDM frame using LDM of twolayers and multiple-physical layer pipes.

Referring to FIG. 16, the LDM frame starts with a bootstrap signalincluding version information of the system or general signalinginformation. The L1 signaling signal which includes code rate,modulation information, number information of physical layer pipes mayfollow the bootstrap as a preamble.

The common Physical Layer Pipe (PLP) in a form of burst may betransferred following the preamble (L1 SIGNAL). In this case, the commonphysical layer pipe may transfer data which can be shared with otherphysical layer pipes in the frame.

The Multiple-Physical Layer Pipes for servicing broadcasting signalswhich are different from each other may be transferred using LDM schemeof two layers. In this case, the service (720p or 1080p HD, etc.) whichneeds robust reception performance such as indoor/mobile may use thecore layer (upper layer) data physical layer pipes. In this case, thefixed reception service (4K-UHD or multiple HD, etc.) which needs hightransfer rate may use the enhanced layer (lower layer) data physicallayer pipes.

If the multiple physical layer pipes are layered-division-multiplexed,it can be seen that the total number of physical layer pipes increases.

In this case, the core layer data physical layer pipe and the enhancedlayer data physical layer pipe may share the time interleaver forreducing complexity and memory size. In this case, the core layer dataphysical layer pipe and the enhanced layer data physical layer pipe mayhave the same physical layer pipe size (PLP size), and may have physicallayer pipe sizes different from each other.

In accordance with the embodiments, the layered-divided PLPs may havePLP sizes different from one another, and information for identifyingthe stat position of the PLP or information for identifying the size ofthe PLP may be signaled.

FIG. 17 is a diagram showing another example of a LDM frame using LDM oftwo layers and multiple-physical layer pipes.

Referring to FIG. 17, the LDM frame may include the common physicallayer pipe after the bootstrap and the preamble (L1 SIGNAL). The corelayer data physical layer pipes and the enhanced layer data physicallayer pipes may be transferred using two-layer LDM scheme after thecommon physical layer pipe.

In particular, the core layer data physical layer pipes and the enhancedlayer data physical layer pipes of FIG. 17 may correspond to one typeamong type 1 and type 2. The type 1 and the type 2 may be defined asfollows:

Type 1 PLP

It is transferred after the common PLP if the common PLP exists

It is transferred in a form of burst (one slice) in the frame

Type 2 PLP

It is transferred after the type 1 PLP if the type 1 PLP exists

It is transferred in a form of two or more sub-slices in the frame

The time diversity and the power consumption increase as the number ofsub-slices increases

In this case, the type 1 PLP may correspond to a non-dispersed PLP, andthe type 2 PLP may correspond to a dispersed PLP. In this case, thenon-dispersed PLP may assigned for contiguous data cell indices. In thiscase, the dispersed PLP may assigned to two or more subslices.

FIG. 18 is a diagram showing an application example of LDM frame usingLDM of two layers and multiple physical layer pipes.

Referring to FIG. 18, the common physical layer pipe (PLP(1,1)) may beincluded after the bootstrap and the preamble in the LDM frame. The dataphysical layer pipe (PLP(2,1)) for robust audio service may be includedin the LDM frame using the time-division scheme.

Moreover, the core layer data physical layer pipe (PLP(3,1)) formobile/indoor service (720p or 1080p HD) and the enhanced layer dataphysical layer pipe (PLP(3,2)) for high data rate service (4K-UHD ormultiple HD) may be transferred using 2-layer LDM scheme.

FIG. 19 is a diagram showing another application example of a LDM frameusing LDM of two layers and multiple physical layer pipes.

Referring to FIG. 19, the LDM frame may include the bootstrap, thepreamble, the common physical layer pipe (PLP(1,1)). In this case, therobust audio service and mobile/indoor service (720p or 1080p HD) may betransferred using core layer data physical layer pipes(PLP(2,1),PLP(3,1)), and the high data rate service (4K-UHD or multipleHD) may be transferred using the enhanced layer data physical layerpipes (PLP(2,2),PLP(3,2)).

In this case, the core layer data physical layer pipe and the enhancedlayer data physical layer pipe may use the same time interleaver.

In this case, the physical layer pipes (PLP(2,2),PLP(3,2)) which providethe same service may be identified using the PLP_GROUP_ID indicating thesame PLP group.

In accordance with the embodiment, the service can be identified usingthe start position and the size of each physical layer pipe withoutPLP_GROUP_ID when the physical layer pipes which have sizes differentfrom each other for different LDM layers are used.

Although multiple physical layer pipes and layers corresponding to thelayered division multiplexing are identified by PLP(i,j) in FIG. 18 andFIG. 19, the PLP identification information and the layer identificationinformation may be signaled as fields different from each other.

In accordance with the embodiment, different layers may use PLPs havingdifferent sizes. In this case, each service may be identified using thePLP identifier.

The PLP start position and the PLP size may be signaled for each PLPwhen PLPs having different sizes are used for different layers.

The following pseudo code is for showing an example of fields includedin the preamble according to an embodiment of the present invention. Thefollowing pseudo code may be included in the L1 signaling information ofthe preamble.

[Pseudo Code] SUB_SLICES_PER_FRAME (15 bits) NUM_PLP (8 bits) NUM_AUX (4bits) AUX_CONFIG_RFU (8 bits) for i=0.. NUM_RF-1 { RF_IDX (3 bits)FREQUENCY (32 bits) } IF S2==‘xxxl’ { FEF_TYPE (4 bits) FEF_LENGTH (22bits) FEF_INTERVAL (8 bits) } for i=0 .. NUM_PLP-1 { NUM_LAYER (2~3bits)  for j=0 .. NUM_LAYER-1{  / * Signaling for each layer */  PLP_ID(i, j) (8 bits)  PLP_GROUP_ID (8 bits)  PLP_TYPE (3 bits) PLP_PAYLOAD_TYPE (5 bits)  PLP_COD (4 bits)  PLP_MOD (3 bits)  PLP_SSD(1 bit)  PLP_FEC_TYPE (2 bits)  PLP_NUM_BLOCKS_MAX (10 bits) IN_BAND_A_FLAG (1 bit)  IN_BAND_B_FLAG (1 bit)  PLP_MODE (2 bits) STATIC_PADDING_FLAG (1 bit)  IF (j > 0)   LL_INJECTION_LEVEL (3~8 bits) } / * End of NUM_LAYER loop */ / * Common signaling for all layers */FF_FLAG (1 bit) FIRST_RF_IDX (3 bits) FIRST_FRAME_IDX (8 bits)FRAME_INTERVAL (8 bits) TIME_IL_LENGTH (8 bits) TIME_IL_TYPE (1 bit)RESERVED_1 (11 bits) STATIC_FLAG (1 bit) PLP_START (24 bits) PLP_SIZE(24 bits) } / * End of NUM_PLP loop */ FEF_LENGTH_MSB (2 bits)RESERVED_2 (30 bits) for i=0 .. NUM_AUX-1 { AUX{STREAM{TYPE (4 bits)AUX{PRIVATE{CONF (28 bits) }

The NUM_LAYER may correspond to two bits or three bits in the abovepseudo code. In this case, the NUM_LAYER may be a field for identifyingthe number of layers in each PLP which is divided in time. In this case,the NUM_LAYER may be defined in the NUM_PLP loop so that the number ofthe layers can be different for each PLP which is divided in time.

The LL_INJECTION_LEVEL may correspond to 3˜8 bits. In this case, theLL_INJECTION_LEVEL may be a field for identifying the injection level ofthe lower layer (enhanced layer). In this case, the LL_INJECTION_LEVELmay correspond to the injection level information.

In this case, the LL_INJECTION_LEVEL may be defined from the secondlayer (j>0) when the number of layers is two or more.

The fields such as PLP_ID(i,j), PLP_GROUP_ID, PLP_TYPE,PLP_PAYLOAD_TYPE, PLP_COD, PLP_MOD, PLP_SSD, PLP_FEC_TYPE,PLP_NUM_BLOCKS_MAX, IN_BAND_A_FLAG, IN_BAND_B_FLAG, PLP_MODE,STATIC_PADDING_FLAG, etc. may correspond to parameters which are definedfor each layer, and may be defined inside of the NUM_LAYER loop.

In this case, the PLP_ID(i,j) may correspond to the PLP identificationinformation and the layer identification information. For example, the‘i’ of the PLP_ID(i,j) may correspond to the PLP identificationinformation and the ‘j’ of the PLP_ID(i,j) may correspond to the layeridentification information.

In accordance with embodiments, the PLP identification information andthe layer identification information may be included in the preamble asfields different from each other.

Moreover, the time interleaver information such as the TIME_IL_LENGTHand TIME_IL_TYPE, etc., the FRAME_INTERVAL which is related to the PLPsize and fields such as FF_FLAG, FIRST_RF_IDX, FIRST_FRAME_IDX,RESERVED_1, STATIC_FLAG, etc. may be defined outside of the NUM_LAYERloop and inside of the NUM_PLP loop.

In particular, the PLP_TYPE corresponds to type information of thephysical layer pipes and may correspond to 1 bit for identifying oneamong two types, type 1 and type 2. The PLP_TYPE is included in thepreamble without checking a condition of a conditional statementcorresponding to the layer identification information (j) in the abovepseudo code, but the PLP_TYPE may be selectively signaled (transferredonly for the core layer) based on a result (if(j=0)) of comparing thelayer identification information (j) with a predetermined value (0).

The PLP_TYPE is defined in the NUM_LAYER loop in the above pseudo code,but the PLP_TYPE may be defined outside of the NUM_LAYER loop and insideof the NUM_PLP loop.

In the above pseudo code, the PLP_START corresponds to a start positionof the corresponding physical layer pipe. In this case, the PLP_STARTmay identify the start position using cell addressing scheme. In thiscase, the PLP_START may be an index corresponding to a first data cellof the corresponding PLP.

In particular, the PLP_START may be signaled for every physical layerpipe and may be used for identifying services using themultiple-physical layer pipes together with a field for signaling thesize of the PLP.

The PLP_SIZE in the above pseudo code corresponds to size information ofthe physical layer pipes. In this case, the PLP_SIZE may be identical tothe number of data cells assigned to the corresponding physical layerpipe.

That is, the PLP_TYPE may be signaled based on the layer identificationinformation and the PLP_SIZE and the PLP_START may be signaled for everyphysical layer pipe without considering the layer identificationinformation.

The combiner 340 shown in FIG. 3 and FIG. 7 functions to combine thecore layer signal and the enhanced layer signal, and the combining maybe performed on a time interleaver group basis shared by the core layersignal and the enhanced layer signal because the core layer signal andthe enhanced layer signal share one time interleaver.

In this case, the time interleaver group may be set based on the corelayer in terms of memory efficiency and system efficiency.

However, when a time interleaver group is set based on the core layer,there may exist a FEC block that is divided by the time interleavergroup boundary in the enhanced layer. If such a FEC block which isdivided exist, signaling of fields for identifying a portion of the FECblock corresponding to the time interleaver group boundary may berequired.

The time interleaver for the Layered Division Multiplexing may be aconvolutional time interleaver (CTI) or a hybrid time interleaver (HTI).In this case, the convolutional time interleaver may be used when thereis one Physical Layer Pipe in the core layer, and the hybrid timeinterleaver may be used when there are two or more Physical Layer Pipesin the core layer. When the hybrid time interleaver is used, thePhysical Layer Pipes may include only complete FEC blocks.

FIG. 20 is a diagram showing an example in which a convolutional timeinterleaver is used.

Referring to FIG. 20, the subframe includes two layers, the core layerand the enhanced layer.

As the subframe includes only one Physical Layer Pipe (PLP #0) in thecore layer in the example shown in FIG. 20, the time interleavercorresponding to the subframe is a convolutional time interleaver. ThePhysical Layer Pipes in each layer may include an incomplete FEC blockwhen the convolutional time interleaver is used.

Such an incomplete FEC block is located at the edge of the PLP and canbe identified using a field such as “L1D_plp_CTI_fec_block_start”indicating the position of the first complete FEC block in each PLP.

In the example shown in FIG. 20, the Physical Layer Pipe (PLP #0) of thecore layer and the Physical Layer Pipe (PLP #1) of the enhanced layerhave the same start position and size.

In the example shown in FIG. 20, it can be seen that the timeinterleaver group (TI Group) corresponds to the Physical Layer Pipe (PLP#0) of the core layer. The time interleaver group is commonly applied tothe core layer and the enhanced layer, and it is advantageous in termsof memory and system efficiency to be set corresponding to the corelayer.

FIG. 21 is a diagram showing another example in which a convolutionaltime interleaver is used.

Referring to FIG. 21, it can be seen that the starting positions andsizes of the core layer physical layer pipe (PLP #0) and the enhancedlayer physical layer pipe (PLP #1) are different.

If the start position and the size of the core layer physical layer pipe(PLP #0) and the start position and the size of the enhanced layerphysical layer pipe (PLP #1) are different from each other, an emptyarea may be included in the enhanced layer.

As shown in FIG. 21, when the empty area is included at the rear end ofthe enhanced layer physical layer pipe (PLP #1), the enhanced layerphysical layer pipe (PLP #1) is ended with a complete FEC block.

FIG. 22 is a diagram showing an example in which a hybrid timeinterleaver is used.

Referring to FIG. 22, two Physical Layer Pipes (PLP #0, PLP #1) areincluded in the core layer.

Thus, when the core layer is composed of multiple Physical Layer Pipes,a hybrid time interleaver is used.

When a hybrid time interleaver is used, all Physical Layer Pipes of thecore layer and the enhanced layer include only complete FEC blocks.

In this case, some parts of the enhanced layer may be emptied foralignment with the core layer boundary.

FIG. 23 is a diagram showing time interleaver groups in the example ofFIG. 22.

Referring to FIG. 23, it can be seen that the time interleaver groupboundaries are set corresponding to the boundaries of the Physical LayerPipes of the core layer.

Although the time interleaver group includes one core layer physicallayer pipe in FIG. 23, according to an embodiment, the time interleavergroup may include two or more core layer physical pipes.

In the example shown in FIG. 23, one FEC block of the enhanced layer maybe divided by the time interleaver group boundary.

This is because time interleaver group partitioning is performed on acore layer basis, in which case it is possible to signal information foridentifying an incomplete FEC block of the enhanced layer, theincomplete FEC block corresponding to the time interleaver groupboundary.

FIGS. 24 to 26 are diagrams showing a process of calculating the size ofan incomplete FEC block in the example of FIG. 23.

Referring to FIG. 24, the distance (A) between the start position of theenhanced layer physical layer pipe (L1D_plp_start(PLP #2)) and the timeinterleaver group boundary is calculated using the start position of thecore layer physical layer pipe (L1D_plp_start(PLP #0)), the size of thecore layer physical layer pipe (L1D_plp_size(PLP #0)) and the startposition of the enhanced layer physical layer pipe (L1D_plp_start(PLP#2)).

Referring to FIG. 25, the distance (B) between the start position of thedivided FEC block and the time interleaver group boundary is calculatedusing the FEC block size of the enhanced layer.

In this case, the FEC block size may be decided by using the modulationinformation (L1D_plp_mod) corresponding to the enhanced layer and theFEC type information (L1D_plp_fec_type) corresponding to the enhancedlayer.

Referring to FIG. 26, the part (C) of the FEC block of the enhancedlayer corresponding to the boundary between the time interleaver groupsis identified.

Table 3 below shows an example of L1-Detail fields of the preambleaccording to an embodiment of the present invention.

The preamble according to an embodiment of the present invention mayinclude L1-Basic and L1-Detail.

TABLE 3 Syntax # of bits L1_Detail signaling() {  L1D_version 4 L1D_num_rf 3  for L1D_rf_id=1 .. L1D_num_rf {   L1D_rf_frequency 19  } if ( L1B_time_info_flag !=00 ) {   L1D_time_sec 32   L1D_time_msec 10  if ( L1B_time_info_flag !=01) {    L1D_time_usec 10    if (L1B_time_info_flag !=10 ) {     L1D_time_nsec 10    }   }  }  for i=0 ..L1B_num_subframes {   if (i>0) {    L1D_mimo 1    L1D_miso 2   L1D_fft_size 2    L1D_reduced_carriers 3    L1D_guard_interval 4   L1D_num_ofdm_symbols 11    L1D_scattered_pilot_pattern 5   L1D_scattered_pilot_boost 3    L1D_sbs_first 1    L1D_sbs_last 1   }  if (L1B_num_subframes >0) {    L1D_subframe_multiplex 1   }  L1D_frequency_interleaver 1   L1D_num_plp 6   for j=0 .. L1D_num_plp {   L1D_plp_id 6    L1D_plp_lls flag 1    L1D_plp_layer 2   L1D_plp_start 24    L1D_plp_size 24    L1D_plp_scrambler type 2   L1D_plp_fec type 4    if (L1D_plp fec_type ∈{0,1,2,3,4,5 }) {    L1D_plp_mod 4     L1D_plp_cod 4    }    L1D_plp_TI_mode 2    if (L1D_plp_TI_mode=00) {     L1D_plp_fec_block_start 15    }    if (L1D_plp_TI_mode=01) {     L1D_plp_CTI_fec_block_start 22    }    if(L1D_num_rf>0) {     L1D_plp_num_channel_bonded 3     if(L1D_plp_num_channel_bonded >0) {      L1D_plp_channel_bonding_format 2     for k=0 .. L1D_plp_num_channel_bonded {       L1D_plp_bonded_rf_id3      {     {    {    if (i=0 && L1B_first_sub_mimo=1) || (i >1 &&L1D_mimo=1) {     L1D_plp_stream_combining 1     L1D_plp_IQ_interleaving1     L1D_plp_PH 1    }    if (L1D_plp layer=0) {     L1D_plp_type 1    if L1D_plp_type=1 {      L1D_plp_num_subslices 14     L1D_plp_sub_slice_interval 24     }    L1D_plp_TI_extended_interleaving 1     if (L1D_plp_TI_mode=01) {     L1D_plp_CTI_depth 3      L1D_plp_CTI_start_row 11     }else if(L1D_plp_TI_mode=10) {      L1D_plp_HTI_inter_subframe 1     L1D_plp_HTI_num_ti blocks 4 12  L1D_plp_HTI_num_fec_blocks_max     if (L1D_plp_HTI_inter_subframe=0) { 12  L1D_plp_HTI_num_fec_blocks     } else {       for (k=0.. L1D_plp_HTI_num_ti_blocks) { 12 L1D_plp_HTI_num_fec_blocks       } 1       L1D_plp_HTI_cell_interleaver1     } 1    } else {     L1D_plp_ldm_injection level 5    }   }  } L1D_reserved as needed  L1D_crc 32 }

All fields corresponding to assigned bits in Table 3 may correspond tounsigned integer most significant bit first (uimsbf) format.

Among fields in Table 3, L1D_plp_layer may be a field for representing alayer corresponding to each physical layer pipe. L1D_plp_start maycorrespond to start position information of the current PLP, and mayindicate an index of the first data cell of the current PLP.L1D_plp_size may correspond to size information of the current PLP, andmay indicate the number of data cells allocated to the current PLP. Inthis case, L1D_plp_size may be greater than zero.

L1D_plp_fec_type may correspond to FEC type information of the currentPLP, and may indicate the Forward Error Correction (FEC) method used forencoding the current PLP.

For example, L1D_plp_fec_type=“0000” may correspond to BCH and 16200LDPC, L1D_plp_fec_type=“0001” may correspond to BCH and 64800 LDPC,L1D_plp_fec_type=“0010” may correspond to CRC and 16200 LDPC,L1D_plp_fec_type=“0011” may correspond to CRC and 64800 LDPC,L1D_plp_fec_type=“0100” may correspond to 16200 LDPC, andL1D_plp_fec_type=“0101” may correspond to 64800 LDPC.

L1D_plp_mod may indicate modulation information of the current PLP. Inthis case, L1D_plp_mod may be signaled only if L1D_plp_fec_typesatisfies a predetermined condition as shown in Table 3.

For example, L1D_plp_mod=“0000” may correspond to QPSK,L1D_plp_mod=“0001” may correspond to 16QAM-NUC, L1D_plp_mod=“0010” maycorrespond to 64QAM-NUC, L1D_plp_mod=“0011” may correspond to256QAM-NUC, L1D_plp_mod=“0100” may correspond to 1024QAM-NUC andL1D_plp_mod=“0101” may correspond to 4096QAM-NUC. In this case,L1D_plp_mod can be set to “0100” or “0101” only if L1D_plp_fec_typecorresponds to 64800 LDPC.

L1D_plp_TI_mode indicates the time interleaving mode of the PLP.

For example, L1D_plp_TI_mode=“00” may represent no time interleavingmode, L1D_plp_TI_mode=“01” may represent convolutional time interleavingmode and L1D_plp_TI_mode=“10” may represent hybrid time interleavingmode.

L1D_plp_fec_block_start may correspond to start position information ofthe first complete FEC block in the physical layer pipe.L1D_plp_fec_block_start may be signaled only if L1D_plp_TI_mode=“00”.

When the Layered Division Multiplexing is used, L1D_plp_fec_block_startmay be signaled separately for each layer since the start positions ofthe first FEC blocks in each layer can be different.

L1D_plp_CTI_fec_block_start may correspond to start position informationof the first complete block in the physical layer pipe.L1D_plp_CTI_fec_block_start may be signaled only ifL1D_plp_TI_mode=“01”.

In this case, more bits may be allocated to L1D_plp_CTI_fec_block_startthan L1D_plp_fec_block_start.

As described above, when L1D_plp_TI_mode=“10”, all PLPs include only thecomplete FEC blocks, so there is no need to separately signal the startposition of the first FEC block.

L1D_plp_HTI_num_fec_blocks may correspond to the number of FEC blockscontained in the current interleaving frame for the physical layer pipeof the core layer.

In this case, it can be seen that each of fields (L1D_plp_CTI_depth,L1D_plp_CTI_start_row) corresponding to a Convolutional timeinterleaving and fields (L1D_plp_HTI_inter_subframe,L1D_plp_HTI_num_ti_blocks, L1D_plp_HTI_num_fec_blocks max,L1D_plp_HTI_num_fec_blocks, L1D_plp HTI cell interleaver, etc.)corresponding to a Hybrid time interleaving according to whetherL1D_plp_TI_mode is 01 or 10 when L1D_plp_layer is 0 (core layer) aresignaled as the time interleaver information.

In this case, L1D_plp_CTI_depth may indicate the number of rows used inthe Convolutional time interleaver and L1D_plp_CTI_start_row mayindicate the position of interleaver selector at the start of thesubframe.

In this case, L1D_plp_HTI_inter_subframe may indicate the Hybrid timeinterleaving mode, and L1D_plp_HTI_num_ti_blocks may indicate the numberof TI blocks per interleaving frame or the number of subframes overwhich cells from one TI block are carried, andL1D_plp_HTI_num_fec_blocks max may indicate one less than the maximumnumber of FEC blocks per interleaving frame for the current PhysicalLayer Pipe, and L1D_plp_HTI_num_fec_blocks may indicate one less thanthe number of FEC blocks contained in the current interleaving frame forthe current Physical Layer Pipe, and L1D_plp_HTI_cell_interleaver mayindicate whether the cell interleaver is used or not.

In this case, a field such as L1D_plp_TI_mode may be signaled separatelyfrom the time interleaver information signaled based on the core layer.

FIG. 27 is a diagram for explaining the number of bits required forL1D_plp_fec_block_start when L1D_plp_TI_mode=“00”.

Referring to FIG. 27, it can be seen that cell address of FEC blockstart position before time interleaving (C_in) and cell address of FECblock start position after time interleaving (C_out) are identical whenL1D_plp_TI_mode=“00” (no time interleaving).

In the case of no time interleaving as FIG. 27, it can be seen that theConvolutional interleaving is performed with a depth of 0.

In this case, L1D_plp_fec_block_start is defined after time interleavingso that C_out may be signaled as L1D_plp_fec_block_start for eachPhysical Layer Pipe in the subframe.

The longest FEC block may have a length of 64800/2=32400 when the LDPCcodeword is 16200 or 64800 and the modulation order is 2, 4, 6, 8, 10and 12.

As 32400 can be expressed by 15 bits, assigning 15 bits toL1D_plp_fec_block_start may cover the case of L1D_plp_TI_mode=“00”.

FIGS. 28 and 29 are diagrams for explaining the number of bits requiredfor L1D_plp_CTI_fec_block_start when L1D_plp_TI_mode=“01”.

Referring to FIG. 28, it can be seen that cell address of FEC blockstart position before time interleaving (C in) and cell address of FECblock start position after time interleaving (C_out) are differentbecause of interleaving when L1D_plp_TI_mode=“01” (Convolutional timeinterleaving).

In this case, L1D_plp_CTI_fec_block_start is defined after timeinterleaving so that C_out may be signaled asL1D_plp_CTI_fec_block_start for each Physical Layer Pipe in thesubframe.

Referring to FIG. 29, it can be seen that a convolutional timeinterleaver having a depth of 4 operates with C_in as an input and C_outas an output.

In this case, 0 corresponds to the 0th row, 1 corresponds to the 1strow, 2 corresponds to the 2nd row, 3 corresponds to the 3rd row, 4corresponds to the 0th row, 5 corresponds to the 1st row, 6 correspondsto the 2nd row, 7 corresponds to the 3rd row, 8 corresponds to the 0throw, 9 corresponds to the 1st row, 10 corresponds to the 2nd row in thecase of the input.

At First, 0, 4, 8, etc. corresponding to the 0th row are output withoutdelay.

1, 5, 9, etc. corresponding to the 1st row are output with 4 delays.

2, 6, 10, etc. corresponding to the 2nd row are output with 8 delays.

3, 7, etc. corresponding to the 3rd row are output with 12 delays.

That is, it can be seen that (n×4) delays occur for the n-th row.

Although the example of depth 4 (the number of rows of the timeinterleaver is 4) is explained in FIG. 29, the input corresponding tothe n-th row is delayed by (n×N_row) when the number of rows of the timeinterleaver is N_row.

In this case, cell address of FEC block start position after timeinterleaving (L1D_plp_CTI_fec_block_start) may be calculated as (C_in+(n×N_row)). In this case, n is a row corresponding to C_in and may bedetermined by L1D_CTI_start_row among the time interleaving informationsignaled by L1-Detail. In this case, n may be ((LID CTI start row+C_in)% N_row). In this case, L1D_CTI_start_row may indicate the position ofthe interleaver selector at the start of the subframe.

That is, L1D_plp_CTI_fec_block_start can be calculated by adding a delaycaused by time interleaving to C_in.

To calculate the number of bits required for signalingL1D_plp_CTI_fec_block_start, the maximum value ofL1D_plp_CTI_fec_block_start is required. As already shown above, themaximum value of C_in is 32400, the maximum value of n is N_row−1 andN_row may be 1024 at most in the case of non-extended interleaving. Inthis case, the maximum value of L1D_plp_CTI_fec_block_start is(32400+(1024−1)λ1024)=1079952. 1079952 can be signaled using at least 21bits.

N_row may be 1448 at most in the case of extended interleaving. In thiscase, the maximum value of L1D_plp_CTI_fec_block_start is(32400+(1448-1)X¹⁴⁴⁸)=2127656. 2127656 can be signaled using at least 22bits.

Accordingly, since the maximum value of L1D_plp_fec_block_start isidentical to the maximum value of C_in when L1D_plp_TI_mode=“00” and themaximum value of L1D_plp_CTI_fec_block_start is the sum of the maximumvalue of C_in and the delay due to the interleaving whenL1D_plp_TI_mode=“01”, an efficient signaling is possible when the numberof bits used for signaling L1D_plp CTI_fec_block_start is larger thanthe number of bits used for signaling L1D_plp_fec_block_start.

Since all Physical Layer Pipes of the core layer and the enhanced layerinclude only complete FEC blocks when L1D_plp_TI_mode=“10”, the startposition of all Physical Layer Pipes becomes the start position of thefirst complete FEC block so that there is no need to signal the fieldsuch as L1D_plp_fec_block_start or L1D_plp_CTI_fec_block_start.

FIG. 30 is a diagram showing an insertion of Enhanced Layer dummy valueswhen the HTI mode is used with Layered-Division Multiplexing.

Referring to FIG. 30, the dummy values (Dummy) are inserted in theenhanced layer data (L1D_PLP_layer=1) of the time interleaver group(TI_Group_1).

Let a PLP group represent the complete set of PLPs associated withdelivering a particular end product to receivers within a subframe.

A PLP group may contain at least one Core PLP and may also contain oneor more Enhanced PLPs when Layered-Division Multiplexing is in use.

When time interleaving is configured as HTI mode, which uses an integernumber of FEC Blocks for the actual PLP data, the total number of cellsof Core PLP(s) may be different from that of Enhanced PLP(s) within aparticular PLP group depending on ModCod configuration of each PLP. Insuch cases, Enhanced Layer dummy values may be inserted after the actualdata cells of the last Enhanced PLP in the PLP group so that the totalnumber of Enhanced Layer cells is the same as the total number of CoreLayer cells in that PLP group. Dummy values may not be inserted in theCore Layer since time interleaver groups are configured with respect toCore PLP(s).

The insertion of Enhanced Layer dummy values may be performed after theBICM stages and before Core PLP(s) and Enhanced PLP(s) are combined.

For the generation of Enhanced Layer dummy values, a scrambling sequencemay be used and this scrambling sequence may be reinitialized for eachrelevant PLP group. Moreover, this sequence may be modulated by usingthe same constellation mapping that is used for the last Enhanced PLP inthe current PLP group.

The Enhanced Layer dummy values may have the same power as theimmediately preceding Enhanced PLP within the same PLP group so that thesame scaling factor and normalizing factor which are used for the actualdata are applied for the Enhanced Layer dummy values.

FIG. 31 is a diagram showing an example of the shift register used forgenerating the dummy values according to the exemplary embodiment of thepresent invention.

Referring to FIG. 31, the sequence is generated by the 16-bit shiftregister corresponding to the generator polynomial of1+X³+X⁶+X⁷+X¹¹+X¹²+X¹³+X¹⁶.

The register of FIG. 31 may be initialized by the initial sequence of0xF180 (1111 0001 1000 0000). As explained above, the scramblingsequence may be reinitialized for each relevant PLP group.

In an example of FIG. 31, eight of the shift register outputs (D⁷, D⁶, .. . , D⁰) may be output bits. After output of the output bits, the bitsin the shift register may be shifted once. After the shift, the registerX¹⁴ stores 0 which corresponds to 1 exclusive or (XOR) 1, the registerX¹³ stores 1 which corresponds to 1 XOR 0, the register X¹² stores 1which corresponds to 1 XOR 0, X¹¹ stores 0 which is previously stored inthe register X^(th), the register X⁷ stores 1 which corresponds to 1 XOR0, the register X⁴ stores 1 which corresponds to 1 XOR 0, the registerX³ stores 0 which is previously stored in the register X², and theregister X stores 1 which is previously stored in the register X¹⁶.

Therefore, the output sequence (scrambling sequence) may be 1100 00000110 1101 0011 1111 . . . (MSB first, or D⁷, D⁶, . . . , D⁰, D⁷, D⁶, . .. ) in the example of FIG. 31.

As explained above, each physical layer pipe (PLP) may be configuredwith one of the no time interleaving mode, convolutional timeinterleaving (CTI) mode or hybrid time interleaving (HTI) mode.

The time interleaving mode for a PLP may be indicated byL1D_plp_TI_mode, and the time interleaving mode indicated for anenhanced PLP shall be the same as the time interleaving mode indicatedfor the core PLP(s) with which the enhanced PLP is layered divisionmultiplexed.

When a complete delivered product is composed of only a singleconstant-cell-rate PLP or is composed of a single constant-cell-ratecore PLP and one or more constant-cell-rate enhanced PLPs layereddivision multiplexed with that core PLP, the PLP(s) comprising thatcomplete delivered product may be configured with one of the no timeinterleaving mode, the convolutional time interleaving mode or thehybrid time interleaving mode.

When a complete delivered product is composed of PLPs havingcharacteristics different from those described in the precedingparagraph, the PLPs comprising that complete delivered product may beconfigured with one of the no time interleaving mode or the hybrid timeinterleaving mode.

In this case, the complete delivered product may correspond to oneservice. That is, the complete delivered product may include all PLPdata required for one service.

The time interleaving mode(s) for the PLPs of a particular completedelivered product may be configured independently of the timeinterleaving mode(s) for the PLP(s) of any other delivered productstransmitted within the same RF channel. When a particular deliveredproduct contains multiple core PLPs and/or PLPs that are not layereddivision multiplexed, those PLPs may be configured with the same ordifferent time interleaving modes (i.e., no time interleaving modeand/or hybrid time interleaving mode) and/or the same or different timeinterleaver parameters.

FIG. 32 is a diagram showing types of the time interleaving mode.

Referring to FIG. 32, the time interleaving mode is largely divided intointra-subframe interleaving and inter-subframe interleaving.

Intra-subframe interleaving corresponds to the case where interleavingoccurs within a subframe. In this case, the interleaving frame is mappedto one subframe. That is, if intra-subframe interleaving is performed,the decoder may decode the corresponding physical layer pipe within thesubframe.

Inter-subframe interleaving corresponds to the case where theinterleaving is out of one subframe range. In this case, theinterleaving frame is mapped to a plurality of subframes. That is, ifinter-subframe interleaving is performed, the decoder may need data ofsubframes other than one subframe in order to decode the correspondingphysical layer pipe.

As shown in FIG. 32, the no time interleaving mode (NO TI) correspondsto intra-subframe interleaving, and the convolutional time interleavingmode (CTI) corresponds to inter-subframe interleaving. In this case, theno time interleaving mode (NO TI) can be seen as an interleaving modewith an interleaving depth of 0.

The hybrid time interleaving mode (HTI) may correspond to intra-subframeinterleaving or may correspond to inter-subframe interleaving. In caseof CDL (Convolutional Delay Line) OFF, the hybrid time interleaving modemay correspond to intra-subframe interleaving. In case of CDL ON, thehybrid time interleaving mode may correspond to inter-subframeinterleaving.

The field of L1D_plp_HTI_inter_subframe may be used for identifyingintra-subframe interleaving or inter-subframe interleaving in case ofthe hybrid time interleaving mode. For example, the time interleavingmode corresponds to intra-subframe interleaving in case ofL1D_plp_HTI_inter_subframe=0, and the time interleaving mode correspondsto inter-subframe interleaving in case of L1D_plp_HTI_inter_subframe=1.

The time interleaving mode or the parameters related to the timeinterleaving mode may be set for each core layer physical layer pipe.Therefore, the case where some of core layer physical layer pipes whichare layered division multiplexed with one enhanced layer physical layerpipe use intra-subframe interleaving and others use inter-subframeinterleaving can occur if a decoding process is not considered forsetting the time interleaving mode or the parameters related to the timeinterleaving.

FIG. 33 is a diagram showing a case where the intra-subframeinterleaving and the inter-subframe interleaving are used at the sametime.

Referring to FIG. 33, three core layer physical layer pipes (CORE PLP#0, CORE PLP #1, CORE PLP #2) are layered division multiplexed with oneenhanced layer physical layer pipe (ENHANCED PLP #3).

The first core layer physical layer pipe (CORE PLP #0) corresponds tointra-subframe interleaving because it corresponds to HTI mode with CDLOFF. The second core layer physical layer pipe (CORE PLP #1) correspondsto inter-subframe interleaving because it corresponds to HTI mode withCDL ON. The third core layer physical layer pipe (CORE PLP #2)corresponds to intra-subframe interleaving because it corresponds to NOTI mode.

Therefore, the first and the third core layer physical layer pipes (COREPLP #0, CORE PLP #2) may be decoded immediately but the second corelayer physical layer pipe (CORE PLP #1) can be decoded after waiting fordecoding the number (N_(IU)−1) of subframes. In this case, the numbercorresponds to a time interleaving unit (N_(IU)). In this case, the timeinterleaving unit (N_(IU)) may be the number of subframes to which cellsfrom one time interleaving block in case of inter-subframe interleaving.

In an example of FIG. 33, pieces of the enhanced layer physical layerpipe have different decoding timing and this means that additionallatency and buffers are needed for decoding that enhanced layer physicallayer pipe.

FIG. 34 is a diagram showing subframes in case that the intra-subframeinterleaving and the inter-subframe interleaving are used at the sametime.

Referring to FIG. 34, three core layer physical layer pipes (PLP #0, PLP#1, PLP #2) are layered division multiplexed with one enhanced layerphysical layer pipe (PLP #3) over three subframes.

In this case, pieces (PLP #3-A, PLP #3-B, PLP #3-C) of the enhancedlayer physical layer pipe may have five, two and four FEC blocks,respectively and the time interleaving unit (NO of the core layerphysical layer pipe (PLP #1) may be 3. In this case, the enhanced layerphysical layer pipe (PLP #3) has to wait for decoding subframescorresponding to the time interleaving unit (N_(IU)).

In an example of FIG. 34, timing of outputting the enhanced layer cells(removal of core layer cells) may be #0, 1, 2, 3, 4, 7, 8, 9, 10, 11,12, 13, 14, 15, 18, 19, 20, 21, 22, 23, 24, 25, 26, 5, 6, 29, 30, 31,32, . . . . Therefore, parts (#5, #6) of the first subframe (SUBFRAME#0) is output after waiting two subframes (SUBFRAME #1, SUBFRAME #2) andthis may be a problem of decoding timing.

In order to solve such a problem of decoding timing, when a plurality ofcore layer physical layer pipes are layered division multiplexed withone enhanced layer physical layer pipe, it may be effective in solvingthe decoding timing problem and in reducing decoding complexity relatedto the decoding timing problem to use intra-subframe interleaving forall core layer physical layer pipes (which are layered divisionmultiplexed with one enhanced layer physical layer pipe) or to useinter-subframe interleaving for all core layer physical layer pipes.

Even if a plurality of core layer physical layer pipes which are layereddivision multiplexed with one enhanced layer physical layer pipe all useinter-subframe interleaving, the time interleaving units (N_(IUS)) ofthe core layer physical layer pipes may be different from each other.

That is, decoding complexity may increase even if all core layerphysical layer pipes which are layered division multiplexed with oneenhanced layer physical layer pipe use inter-subframe interleaving.

FIG. 35 is a diagram showing a case where time interleaving units whichare different one another are used at the same time.

Referring to FIG. 35, three core layer physical layer pipes (CORE PLP#0, CORE PLP #1, CORE PLP #2) are layered division multiplexed with oneenhanced layer physical layer pipe (ENHANCED PLP #3).

Three core layer physical layer pipes (CORE PLP #0, CORE PLP #1, COREPLP #2) all use inter-subframe interleaving as these all correspond tohybrid time interleaving mode (HTI mode) with CDL ON. However, the timeinterleaving unit (NO of the first core layer physical layer pipe (COREPLP #0) is 2, the time interleaving unit (NO of the second core layerphysical layer pipe (CORE PLP #1) is 4, the time interleaving unit(N_(IU)) of the third core layer physical layer pipe (CORE PLP #2) is 3.

Therefore, the first core layer physical layer pipe (CORE PLP #0) shallwait for 1 subframe, the second core layer physical layer pipe (CORE PLP#1) shall wait 3 subframes, and the third core layer physical layer pipe(CORE PLP #2) shall wait for 2 subframes.

In an example of FIG. 35, pieces of the enhanced layer physical layerpipe have different decoding timing and this means that additionallatency and buffers are needed for decoding that enhanced layer physicallayer pipe.

Therefore, it may be effective in solving the decoding timing problemand in reducing decoding complexity related to the decoding timingproblem to use inter-subframe interleaving and the same timeinterleaving unit for all core layer physical layer pipes which arelayered division multiplexed with one enhanced layer physical layerpipe.

However, the decoding problem may occur according to the subframestructure even if all core layer physical layer pipes which are layereddivision multiplexed with one enhanced layer physical layer pipe useinter-subframe interleaving and the same time interleaving unit.

FIG. 36 is a diagram showing subframes in case that the same timeinterleaving unit is used at the same time.

Referring to FIG. 36, two core layer physical layer pipes (CORE PLP #0,CORE PLP #1) are layered division multiplexed with one enhanced layerphysical layer pipe (ENHANCED PLP #3) in the first subframe (SUBFRAME0).

Moreover, one core layer physical layer pipe (CORE PLP #1) is layereddivision multiplexed with one enhanced layer physical layer pipe(ENHANCED PLP #3) in each of the second and the third subframes(SUBFRAME 1, 2).

Moreover, one core layer physical layer pipe (CORE PLP #0) is layereddivision multiplexed with one enhanced layer physical layer pipe(ENHANCED PLP #3) in the fourth subframe (SUBFRAME #3).

In this case, two core layer physical layer pipes (CORE PLP #0, CORE PLP#1) of the first subframe all correspond to inter-subframe interleavingand use the same time interleaving unit (N_(IU)=3).

The core layer physical layer pipe (CORE PLP #1) shall wait up to thethird subframe (SUBFRAME 2) but the core layer physical layer pipe (COREPLP #0) shall wait after the fourth subframe (SUBFRAME 3). It is becausethe structure of the subframes after the first subframe (SUBFRAME 0) isdifferent from each other.

In an example of FIG. 36, pieces of the enhanced layer physical layerpipe have different decoding timing in spite of the same timeinterleaving unit and this means that additional latency and buffers areneeded for decoding that enhanced layer physical layer pipe.

As explained with reference to FIG. 33˜FIG. 36, the decoding problemoccurs because pieces of one enhanced layer physical layer pipes havedifferent decoding timing when a plurality of core layer physical layerpipes are layered division multiplexed with the enhanced layer physicallayer pipe.

When an enhanced layer physical layer pipe is spread over multiple timeinterleaving groups, all core layer physical layer pipes associated withthat enhanced layer physical layer pipe may use the same timeinterleaving mode. In this case, either all core layer physical layerpipes associated with that enhanced layer physical layer pipe shall usethe hybrid time interleaving mode or else all core physical layerphysical layer pipes associated with that enhanced layer physical layerpipe shall use the no time interleaving mode.

That is, in this case all core layer physical layer pipes use the sametime interleaving mode, but the use of the convolutional timeinterleaving mode may be prohibited.

According to the embodiments, when all core layer physical layer pipesassociated with that enhanced layer physical layer pipe use theconvolutional time interleaving mode, the interleaving depths(L1D_plp_CTI_depth) of all core layer physical layer pipes may be thesame.

In this case, when all core layer physical layer pipes associated withthat enhanced layer physical layer pipe use the hybrid time interleavingmode, each such core layer physical layer pipe may use intra-subframeinterleaving mode (i.e., L1D_plp_HTI_inter_subframe=0). That is,inter-subframe interleaving may be prohibited when all core layerphysical layer pipes associated with that enhanced layer physical layerpipe use the hybrid time interleaving mode.

According to the embodiment, when core layer physical layer pipesassociate with that enhanced layer physical layer pipe use the hybridtime interleaving mode corresponding to inter-subframe interleaving, allcore layer physical layer pipes may use the same time interleaving unit.

In this case, when all core layer physical layer pipes associated withthat enhanced layer physical layer pipe use no time interleaving mode,each such core layer physical layer pipe may consist of an integernumber of FEC blocks within each subframe.

In this case, dummy modulation values may be used in order to achieve aninteger number of FEC blocks per subframe.

Depending upon the exact subframe configuration and physical layer pipemultiplexing parameters, the available data cells of a subframe may befully or partially occupied by physical layer pipe data. In the eventthat not all of the available data cells have physical layer pipe datamapped to them, it is important that these unoccupied data cells aremodulated rather than remaining as unmodulated null cells in order toensure a constant transmit power. This may be accomplished by assigningpseudo-random dummy modulation values to the unoccupied data cells.

Unoccupied data cells could conceivably occur anywhere within asubframe, depending upon the exact physical layer pipe multiplexingparameters. Therefore, all of the available data cells of a subframe mayfirst be filled with dummy modulation values, and then the cellmultiplexing process may overwrite the dummy modulation values ofoccupied data cells with actual physical layer pipe data. This approachensures that every available data cell in a subframe is modulated eitherby a physical layer pipe cell or by a dummy modulate value.

N_(cell) may be the total number of available data cells in a subframeso that those data cells are indexed from 0 to N_(cell)−1. d_(i) may bethe dummy modulation value for the data cell with index i (0≤i<N_(cell))and b_(i) (0≤i<N_(cell)) may represent the ith value of the scramblingsequence explained with FIG. 31.

In this case, the real value of the dummy modulation value for the datacell with index i (0≤i<N_(cell)) may be (1−2*b_(i)) and the imaginaryvalue of the dummy modulation value may be 0. That is, the dummymodulation values are generated by mapping a value of the scramblingsequence into one of two phases which are separated by 180 degrees.

Each of the N_(cell) available data cells in the subframe may have itscorresponding dummy modulation value assigned to it prior to anyphysical layer pipe data being multiplexed into the subframe. Followingthe insertion of these dummy modulation values, physical layer pipe databelonging to the current subframe may be mapped to the correspondingdata cells allocated for that physical layer pipe data and may overwritethe dummy modulation values previously assigned to those data cells.

Decoding timing mismatch may be a problem not only for a plurality ofcore layer physical layer pipes that are layered division multiplexedwith one enhanced layer physical layer pipe but also for core layerphysical layer pipes that are not layered-division multiplexed.

FIG. 37 is a diagram showing a case where one complete delivered productis composed of a plurality of physical layer pipes.

Referring to FIG. 37, one complete delivered product includes three corelayer physical layer pipes (PLP #0, PLP #1, PLP #2). In this case, onecomplete delivered product may correspond to one service (SERVICE A). Inthis case, the core layer physical layer pipes (PLP #0, PLP #1, PLP #2)may not layered division multiplexed.

In this case, the first core layer physical layer pipe (PLP #0) maycorrespond to video data of the service (SERVICE A), the second corelayer physical layer pipe (PLP #1) may correspond to the first audiodata of the service (SERVICE A) and the third core layer physical layerpipe (PLP #2) may correspond to the second audio data of the service(SERVICE A).

The first core layer physical layer pipe (PLP #0) may correspond to ahybrid time interleaving mode with CDL OFF, the second core layerphysical layer pipe (PLP #1) may correspond to a hybrid timeinterleaving mode with CDL ON and the third core layer physical layerpipe (PLP #2) may correspond to a hybrid time interleaving mode with CDLON because the characteristics of corresponding data are different foreach of the core layer physical layer pipes consisting of one completedelivered product. In this case, the time interleaving unit (N_(IU)) ofthe core layer physical layer pipe (PLP #1) may be 3 and the timeinterleaving unit (N_(IU)) of the core layer physical layer pipe (PLP#2) may be 4 as shown in FIG. 37.

The core layer physical layer pipe corresponding to intra-subframeinterleaving may be decoded immediately but the core layer physicallayer pipe corresponding to inter-subframe interleaving shall wait forother subframes in case that some of core layer physical layer pipescomprising one complete delivered product correspond to intra-subframeinterleaving and other some of core layer physical layer pipescomprising the complete delivered product correspond to inter-subframeinterleaving.

Moreover, even if both of the core layer physical layer pipes useinter-subframe interleaving, the decoding timing is mismatched when thetime interleaving units (N_(IUS)) of the corer layer physical layerpipes are different from each other.

In an example of FIG. 37, the first physical layer pipe (PLP #0) may bedecoded immediately because it corresponds to intra-subframeinterleaving. The second physical layer pipe (PLP #1) shall wait for twosubframes because it corresponds to inter-subframe interleaving with thetime interleaving unit (N_(IU)) of 3. The third physical layer pipe (PLP#2) shall wait for three subframes because it corresponds tointer-subframe interleaving with the time interleaving unit (N_(IU)) of4.

In an example of FIG. 37, three core layer physical layer pipes havedifferent decoding timing. In this case, the first core layer physicallayer pipe (PLP #0) and the second core layer physical layer pipe (PLP#1) shall be synchronized with the third core layer physical layer pipe(PLP #2) for the service (SERVICE A). Therefore, the first and thesecond core layer physical layer pipes (PLP #0, PLP #1) shall wait threesubframes and this causes unnecessary decoding complexity.

For reducing decoding complexity, when a particular complete deliveredproduct contains multiple core layer physical layer pipes that are notlayered-division multiplexed and all of those core layer physical layerpipes use the hybrid time interleaving mode, either all of those corelayer physical layer pipes may use intra-subframe interleaving or elseall of those core layer physical layer pipes may use inter-subframeinterleaving. That is, all of those core layer physical layer pipes maybe configured with the same value of L1D_plp_HTI_inter_subframe(L1D_plp_HTI_inter_subframe=0 represents intra-subframe interleaving andL1D_plp_HTI_inter_subframe=1 represents inter-subframe interleaving).

When inter-subframe interleaving is used for those core layer physicallayer pipes (L1D_plp_HTI_inter_subframe=1), then all of those core layerphysical layer pipes may use the same time interleaving unit (N_(IU)).

When a particular complete delivered product contains multiple corelayer physical layer pipes that are not layered-division multiplexed andat least one of those core layer physical layer pipes uses the no timeinterleaving mode, any of those core layer physical layer pipesconfigured with the hybrid time interleaving mode shall use theintra-subframe interleaving mode (L1D_plp_HTI_inter_subframe=0). Thatis, the use of inter-subframe interleaving mode may be prohibited forany of those core layer physical layer pipes corresponding to the hybridtime interleaving mode when a particular complete delivered productcontains multiple core layer physical layer pipes that are notlayered-division multiplexed and at least one of those core layerphysical layer pipes uses the no time interleaving mode.

FIG. 38 is a block diagram showing an example of the time interleaver inFIG. 3 or FIG. 7.

Referring to FIG. 38, the time interleaver according to an embodiment ofthe present invention includes a cell interleaver 3810, a twisted blockinterleaver 3820 and a convolutional delay line 3830.

The cell interleaver 3810 interleaves cells in the time interleavingblock.

In this case, the cell interleaver 3810 may arrange input cells in FECblocks into time interleaving blocks. In this case, the timeinterleaving block may be composed of one or more FEC blocks.

In this case, the time interleaving block may be a basic unit foroperations of the cell interleaver 3810, the twisted block interleaver3820 and the convolutional delay line 3830.

In this case, the time interleaving blocks may include different numberof FEC blocks.

In this case, the cell interleaver 3810 may interleave cells within eachFEC block.

In this case, the cell interleaver 3810 may perform cell interleaving bywriting a FEC block into memory and reading the FEC blockpseudo-randomly.

According to the embodiment, the cell interleaver 3810 may be omitted.

The twisted block interleaver 3820 performs intra-subframe interleavingcorresponding to the time interleaving blocks.

The convolutional delay line 3830 performs inter-subframe interleavingusing an output of the twisted block interleaver 3820. That is, theconvolutional delay line 3830 spreads a block-interleaved timeinterleaving block over multiple subframes.

In this case, the twisted block interleaver 3820 may perform theintra-subframe interleaving by performing a column-wise writingoperation and a diagonal-wise reading operation.

In this case, the convolutional delay line 3830 may read only data cellsexcept for virtual cells from the twisted block interleaver 3820.

In this case, the convolutional delay line 3830 may generate (store) newvirtual cells prior to switches moving to a next branch, after each rowof the data cells is written from the twisted block interleaver 3820.

In this case, the new virtual cells may correspond to the numberobtained by subtracting the number of FEC blocks (N_(FEC_TI)) in a timeinterleaving block of an interleaving frame from the maximum number ofthe FEC blocks (N_(FEC_TI_MAX)) corresponding to the time interleavingblock of the interleaving frame for each branch.

In this case, the new virtual cells may not be outputted from theapparatus for time interleaving (the time interleaver).

In this case, the convolutional delay line 3830 may include branchescorresponding to a time interleaving unit (N_(IU)), and each ofremaining branches except for the first branch of the branches mayinclude at least one FIFO register.

In this case, the convolutional delay line 3830 may output only a partof initial values stored in the FIFO register.

In this case, the part of the initial values may correspond to oneinitialization cell for each of the remaining branches.

FIG. 39 is a diagram showing a writing operation of the twisted blockinterleaver in FIG. 38.

Referring to FIG. 39, the cells of the FEC blocks included in the timeinterleaving block are serially written column-wise into the memory.

FIG. 40 is a diagram showing a reading operation of the twisted blockinterleaver in FIG. 38.

Referring to FIG. 40, the cells of the FEC blocks included in the timeinterleaving block are read out diagonal-wise from the memory.

In the embodiment of FIG. 39 and FIG. 40, N_(FEC_TI_MAX) represents themaximum number of FEC blocks in the time interleaving block of theinterleaving frame, and N_(r) represents the number of cells included ineach FEC block.

As shown in FIG. 39 and FIG. 40, the twisted block interleaver mayperform the intra-subframe interleaving by performing the column-wisewriting operation and the diagonal-wise reading operation.

In this case, the twisted block interleaver may skip the virtual FECcells during the reading process as shown in FIG. 40.

FIG. 41 is a block diagram showing an example of the convolutional delayline in FIG. 38.

Referring to FIG. 41, the convolutional delay line according to theembodiment of the present invention consists of N_(IU) branches. Thatis, the convolutional delay line split a time interleaving block intoN_(IU) interleaving units and spread these interleaving units overN_(IU) subframes.

Switch S₀ may connect the twisted block interleaver to the convolutionaldelay line. Switch S₁ may connect the convolutional delay line to theframing block such as the frame builder in FIG. 3 or FIG. 7.

In this case, the movement of the switches S₀ and S₁ may besynchronized. That is, the switches may always point to identicalbranches of the convolutional delay line.

From the last branch of the convolutional delay line the switches maythen move back to the first branch of the convolutional delay line.

Both switches (S₀ and S₁) may move from branch n (n is an integer of0<=n<N_(IU)−1) of the convolutional delay line to the immediatelysubjacent branch n+1 of the convolutional delay line when N_(FEC_TI_MAX)cells, consisting of N_(FEC_TI) data cells and(N_(FEC_TI_MAX)−N_(FEC_TI)) virtual cells, are written to theconvolutional delay line. In this case, N_(FEC_TI_MAX) may represent themaximum number of the FEC blocks in the time interleaving block of theinterleaving frame, N_(FEC_TI) may represent the number of FEC blockscorresponding to data in the time interleaving block of the interleavingframe, and N_(IU) may represent the time interleaving unit. In thiscase, (N_(FEC_TI_MAX)−N_(FEC_TI)) virtual cells may not be read from thetwisted block interleaver but may be new virtual cells for theconvolutional delay line. That is, the new virtual cells may beindependent of the twisted block interleaver and may be newly generatedin the convolutional delay line.

In this case, two switches (S₀ and S₁) may be reset to the first branchof the convolutional delay line (branch 0) at the start of everysubframe.

In this case, virtual cells may not be read from the twisted blockinterleaver and may not be passed on to the convolutional delay line.

However, after each row of N_(FEC_TI) data cells is written from thetwisted block interleaver to the convolutional delay line, a set of(N_(FEC_TI_MAX)−N_(FEC_TI)) new virtual cells for the convolutionaldelay line may then be input to the convolutional delay line prior toswitches S₀ and S₁ moving to the next branch of the convolution delayline.

In this case, virtual cells may not be written to the time interleaveroutput, neither from the twisted block interleaver nor from theconvolutional delay line.

FIG. 42 is a diagram showing an example of operation of the twistedblock interleaver in FIG. 38.

Referring to FIG. 42, the example where the number (N_(r)) of cellsincluded in each FEC block is 8, N_(FEC_TI_MAX) is 5, N_(FEC_TI) is 3,and N_(IU) is 2 is showed.

In the example of FIG. 42, the virtual cells corresponding to twocolumns are stored in the twisted block interleaver, and the twistedblock interleaving is performed through the column-wise writingoperation and the diagonal-wise reading operation.

In the example of FIG. 42, virtual cells are included in the outputmemory of the twisted block interleaver.

FIG. 43 is a diagram showing an example of operation of theconvolutional delay line in FIG. 38.

Referring to FIG. 43, there are two branches in the convolution delayline as N_(IU) is 2, and the second branch includes a FIFO register.

In the example of FIG. 43, the virtual cells read from the twisted blockinterleaver are transferred to the convolutional delay line.

In particular, FIG. 43 represents the first subframe timing in case ofN_(IU)=2. In this timing, all the data corresponding to the secondbranch are the values stored in the FIFO register.

As explained above, the virtual cells may be not included in atransmission signal.

Therefore, the first subframe (subframe #1) may carry “2, 11, 20, 10,19, 6, 5, 14, 23, 8, 22, 16” and the second subframe (subframe #2) maycarry “7, 1, 15, 0, 9, 18, 17, 4, 13, 3, 12, 21” when the memory iswritten and read from the left side to the right side.

In the example of FIG. 43, I₀, I₁, . . . , I₁₉ which were stored in theFIFO register at previous timing and are outputted from the FIFOregister are to be stored in the lower part (the fifth row˜the eighthrow) of the memory corresponding to the convolutional delay line, butthey may be stored in the second row, the fourth row, the sixth row andthe eighth row of the memory corresponding to the convolutional delayline according to the embodiment.

FIG. 44 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 43.

Referring to FIG. 44, the time deinterleaver corresponding to thedecoding process may restore memory data (CDL memory state includingvirtual cells) in FIG. 44 from two subframes through the FIFO register.Moreover, the time deinterleaver may restore data (writing order to TBDImemory) to be inputted to the twisted block deinterleaver from thememory data.

As shown in FIG. 44, virtual cells are spread in the receiver whenvirtual cells are transferred from the twisted block interleaver to theconvolutional delay line. In this case, the receiver shall know thewriting process of virtual cells.

That is, the inverse convolutional delay line of the receiver requiresthe position information of virtual cells and this causes additionalmemory and an increase of complexity in decoding.

FIG. 45 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 42.

Referring to FIG. 45, the positions of the virtual cells should be knownfor performing the twisted block deinterleaving properly. That is, thepositions of virtual cells or at least the number of virtual cells ateach row should be known for correct twisted block deinterleavingoperation in the time deinterleaver of the receiver.

Therefore, the embodiment explained through FIG. 42˜FIG. 45 has aproblem of increasing decoding complexity because the time deinterleavershould know the positions of virtual cells.

FIG. 46 is a diagram showing another example of operation of the twistedblock interleaver in FIG. 38.

Referring to FIG. 46, unlike the example shown in FIG. 42, in theexample shown in FIG. 46, it can be seen that virtual cells belonging tovirtual FEC blocks are skipped during the reading process from thetwisted block interleaver.

That is, the twisted block interleaver does not output virtual cells butoutputs only data cells corresponding to data in an example of FIG. 46.

FIG. 47 is a diagram showing another example of operation of theconvolutional delay line in FIG. 38.

Referring to FIG. 47, it can be seen that virtual cells are not writtenfrom the twisted block interleaver to the convolutional delay line inthe example of FIG. 47.

That is, the convolutional delay line may read only data cells exceptfor virtual cells from the twisted block interleaver and store them, andthen may generate (and store) new virtual cells so that the virtualcells may not be spread.

In this case, it can be seen that the data shown in FIG. 47 read andwrite from left to right when the memory operates in FIFO(First-In-First-Out) scheme. However, the virtual cells denoted with “X”in the example of FIG. 47, may be written to the memory most recentlyfor each row. That is, the writing order to the memory corresponding tothe convolutional delay line in the example of FIG. 47 may be 2, 11, 20,X, X, 19, 6, 15, X, X, 5, 14, 23, X, X, . . .

In this case, virtual cells may be stored corresponding to the leftmost(N_(FEC_TI_MAX)−N_(FEC_TI)) columns of the convolutional delay line whenthe data cells are written from the twisted block interleaver to theconvolution delay line.

Similarly to FIG. 43, FIG. 47 shows the first subframe timing in case of=2, and it can be seen that all the data corresponding to the secondbranch are values stored in the FIFO register at this timing.

In this case, virtual cells may not be included in the transmissionsignal.

Therefore, the first subframe (subframe #1) may carry “2, 11, 20, 19, 6,15, 5, 14, 23, 13, 22, 16”, and the second subframe (subframe #2) maycarry “7, 1, 10, 0, 9, 18, 8, 17, 4, 3, 12, 21” when the memory shown inFIG. 47 is written and read from left to right (excluding virtualcells).

In the example of FIG. 47, I₀, I₁, . . . , I₁₉ which were stored in theFIFO register at previous timing and are outputted from the FIFOregister are to be stored in the lower part (the fifth row˜the eighthrow) of the memory corresponding to the convolutional delay line, butthey may be stored in the second row, the fourth row, the sixth row andthe eighth row of the memory corresponding to the convolutional delayline according to the embodiment.

In the examples of FIG. 43 and FIG. 47, the memory corresponding to theconvolutional delay line is shown for convenience of explanation, andthe convolutional delay line may not include a separate output memoryaccording to the embodiment.

FIG. 48 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 47.

Referring to FIG. 48, the time deinterleaver corresponding to thedecoding process may restore memory data (CDL memory state includingvirtual cells) in FIG. 48 from two subframes through the FIFO register.Moreover, the time deinterleaver may restore data (writing order to TBDImemory) to be inputted to the twisted block deinterleaver from thememory data. Unlike the case of FIG. 44, in the example shown in FIG.48, the positions of virtual cells are known in the decoding process ofthe inverse convolutional delay line, and the virtual cells are notspread (come together).

Therefore, the decoding complexity is lowered in the case of FIG. 48than in the case of FIG. 44.

FIG. 49 is a diagram showing an example of the decoding processcorresponding to the operation in FIG. 46.

Referring to FIG. 49, since the inverse processes of the column-wisewriting operation and the diagonal-wise reading operation in the twistedblock deinterleaving are performed except for the virtual cells, it canbe seen that the deinterleaving can be simpler than the case of FIG. 45.

FIG. 50 is a diagram showing initial values of the FIFO registerincluded in the convolutional delay line.

Referring to FIG. 50, it can be seen that all the data corresponding tothe second branch at the first subframe timing in case of N_(IU)=2 arevalues 5010 which are stored in the FIFO register.

In this case, the convolutional delay line may output only a part ofinitial values stored in the FIFO register.

In this case, the part of the initial values may correspond to oneinitialization cell for each of remaining branches except for the firstbranch of branches corresponding to the time interleaving unit N_(IU).

That is, one cell may be output and remaining cells may not be outputfor each row among the values 5010 stored in the FIFO register.

According to an embodiment, memories corresponding to the twisted blockinterleaver (TBI) and the convolutional delay line (CDL) may operateaccording to FIFO scheme, and the reading and writing for these memoriesmay be performed from right to left. In this case, unlike the case ofFIG. 50, the first row of the twisted block interleaver memory may store2, 11 and 20 from right to left, the second row may store 7, 1, 10 fromright to left, the third row may store 19, 6, 15 from right to left, thefourth row may store 0, 9, 18 from right to left, the fifth row maystore 5, 14, 23 from right to left, the sixth row may store 8, 17, 4from right to left, the seventh row may store 13, 22, 16 from right toleft, and the eighth row may store 3, 12, 21 from right to left.

In this case, the writing and the reading of the FIFO register shown inFIG. 50 may be performed from right to left. In this case, the first rowof the FIFO register may be initialized to I₀, X, X, X, X from right toleft, the second row may be initialized to I₁, X, X, X, X from right toleft, the third row may be initialized to I₂, X, X, X, X from right toleft, and the fourth row may be initialized to I₃, X, X, X, X from rightto left.

In the example of FIG. 50, the memory corresponding to the convolutionaldelay line may be conceptual to illustrate the output of theconvolutional delay line, and the convolutional delay line may notinclude a separate output memory according to an embodiment.

At the timing corresponding to the first subframe, the memory (CDLmemory) corresponding to the convolutional delay line may store the data(20, 11, 2) stored in the first row of the memory corresponding to thetwisted block interleaver, the data (15, 6, 19) stored in the third rowof the memory, the data (23, 14, 5) stored in the fifth row of thememory, the data (16, 22, 13) stored in the seventh row of the memory,and the values initialized to the FIFO register. In this case, the datainitialized to the FIFO register may be stored to the memorycorresponding to the convolutional delay line. That is, at the timingcorresponding to the first subframe, the first row of the memorycorresponding to the convolutional delay line may store 2, 11, 20, X, X(two new virtual cells) from right to left. The third row of the memorycorresponding to the convolutional delay line may store 19, 6, 15, X, X(two new virtual cells) from right to left. The fifth row of the memorycorresponding to the convolutional delay line may store 5, 14, 23, X, X(two new virtual cells) from right to left. The seventh row of thememory corresponding to the convolutional delay line may store 13, 22,16, X, X from right to left.

In this case, the second row of the memory corresponding to theconvolutional delay line may store one initialization cell (I₀) at therightmost side, and then may store four virtual cells. In this case, thefourth row of the memory corresponding to the convolutional delay linemay store one initialization cell (I₁) at the rightmost side, and thenmay store four virtual cells. In this case, the sixth row of the memorycorresponding to the convolutional delay line may store oneinitialization cell (I₂) at the rightmost side, and then may store fourvirtual cells. In this case, the eighth row of the memory correspondingto the convolutional delay line may store one initialization cell (I₃)at the rightmost side, and then may store four virtual cells.

That is, at the timing corresponding to the first subframe, the firstrow of the memory corresponding to the convolutional delay line maystore 2, 11, 20, X, X from right to left, the second row may store I₀,X, X, X, X from right to left, the third row may store 19, 6, 15, X, Xfrom right to left, the fourth row may store I₁, X, X, X, X from rightto left, the fifth row may store 5, 14, 23, X, X from right to left, thesixth row may store I₂, X, X, X, X from right to left, the seventh rowmay store 13, 22, 16, X, X from right to left, and the eighth row maystore I₃, X, X, X, X from right to left. In this case, X may represent avirtual cell. In this case, the first row of the FIFO register shown inFIG. 50 may store 7, 1, 10, X, X from right to left, the second row maystore 0, 9, 18, X, X from right to left, the third row may store 8, 17,4, X, X from right to left and the fourth row may store 3, 12, 21, X, Xfrom right to left.

In this case, the virtual cells stored in the memory corresponding tothe convolutional delay line may not be output from the timeinterleaver. That is, the first subframe may carry “2, 11, 20, I₀, 19,6, 15, I₁, 5, 14, 23, 12, 13, 22, 16, 13” and the second subframe maycarry “ . . . , 7, 1, 10, . . . , 0, 9, 18, . . . , 8, 17, 4, . . . , 3,12, 21”. In this case, “I₀, I₁, I₂, I₃” may correspond to the part ofthe initial values. In this case, “ . . . ” may correspond to the nexttime interleaving block output from the twisted block interleaver.

FIG. 51 is a block diagram showing an example of the time deinterleaverin FIG. 8 or FIG. 12.

Referring to FIG. 51, the time deinterleaver includes inverseconvolutional delay line 5110, the twisted block deinterleaver 5120 andthe cell deinterleaver 5130.

The inverse convolutional delay line 5110 performs the inverse processof the convolutional delay line shown in FIG. 38.

In this case, the inverse convolutional delay line 5110 may predict thepositions of the virtual cells newly generated in the convolutionaldelay line at a transmitter side, and may perform the inverse processbased on the predicted virtual cell positions.

The twisted block deinterleaver 5120 may perform the inverse process ofthe twisted block interleaver shown in FIG. 38.

In this case, the twisted block deinterleaver 5120 may generate newvirtual cells and store them after restoring data cells.

In this case, the twisted block deinterleaver 5120 may predict thepositions of the virtual cells newly generated in the convolutionaldelay line at the transmitter side, and may perform the inverse processbased on the predicted virtual cell positions.

In this case, the twisted block deinterleaver 5120 may perform theinverse process of the column-wise writing operation and thediagonal-wise reading operation of the twisted block deinterleavingexcept for virtual cells.

The cell deinterleaver 5130 performs the inverse process of the cellinterleaver shown in FIG. 38.

FIG. 52 is an operation flowchart showing a method of time interleavingaccording to an embodiment of the present invention.

Referring to FIG. 52, the method according to the embodiment of thepresent invention, the cell interleaving corresponding to cells in thetime interleaving block is performed at step S5210.

According to the embodiment, the step S5210 may be omitted.

Furthermore, in the method according to the embodiment of the presentinvention, the twisted block interleaving corresponding tointra-subframe interleaving is performed at step S5220.

In this case, the step S5220 may perform the twisted block interleavingby using a column-wise writing operation and a diagonal-wise readingoperation.

Furthermore, in the method according to the embodiment of the presentinvention, the inter-subframe interleaving is performed by using anoutput of the twisted block interleaving at step S5230.

In this case, the step S5230 may be performed by using the convolutionaldelay line.

In this case, the convolutional delay line may read only data cellsexcept for virtual cells corresponding to the twisted blockinterleaving.

In this case, the convolutional delay line may generate (store) newvirtual cells prior to switches moving to a next branch, after each rowof the data cells is written from the output of the twisted blockinterleaving.

In this case, the new virtual cells may correspond to the numberobtained by subtracting the number of FEC blocks (N_(FEC_TI)) in a timeinterleaving block of an interleaving frame from the maximum number ofthe FEC blocks (N_(FEC_TI_MAX)) corresponding to the time interleavingblock of the interleaving frame for each branch.

In this case, the new virtual cells may not be outputted from theinter-subframe interleaving.

In this case, the convolutional delay line may include branchescorresponding to a time interleaving unit (N_(IU)), and each ofremaining branches except for the first branch of the branches mayinclude at least one FIFO register.

In this case, the convolutional delay line may output only a part ofinitial values stored in the FIFO register.

In this case, the part of the initial values may correspond to oneinitialization cell for each of the remaining branches.

The method of time deinterleaving according to an embodiment of thepresent invention may be provided in a manner corresponding to FIG. 52.

For example, the method of time deinterleaving according to anembodiment of the present invention may include a step of performinginter-subframe deinterleaving corresponding to an inverse process of thestep S5230 and a step of performing twisted block deinterleavingcorresponding to an inverse process of the step S5220. In this case, themethod of time deinterleaving according to the embodiment of the presentinvention may further include a step of performing cell deinterleavingcorresponding to an inverse process of the step S5210.

The size information and the start position information of the physicallayer pipe may be generated (calculated) based on (with respect to)after time-interleaving. In this case, the size information and thestart position information may be considered in the current subframe.

Core layer cells and enhanced layer cells are combined(super-positioned) before time interleaving process when the layereddivision multiplexing is applied. In this case, the relative position ofthe enhanced layer physical layer pipes to the core layer physical layerpipe may be calculated before time interleaving for easily decoding theenhanced layer physical layer pipe. The cancellation process of the corelayer data cells from the layered division multiplexed data cells in thedecoder may be performed after time deinterleaving.

Both time interleaving and mapping to subframe (cell multiplexing) maybe applied only for the core layer physical layer pipe combined with theenhanced layer physical layer pipes.

On the receiver side (demodulator), the size information (L1D_plp_size)and the start position information (L1D_plp_start) may be used forselecting the desired core layer physical layer pipe. That is, the sizeinformation and the start position information may be used for findingthe data cells of the desired core layer physical layer pipe as an inputof time deintereaver.

When inter-subframe interleaving such as the convolutional delay line isused, the size information (L1D_plp_size) of the core layer physicallayer pipe may have different values according to whether it iscalculated before time interleaving or after time interleaving.

In this case, it is desirable to calculate the position of the corelayer physical layer pipe with respect to after time interleaving.

FIG. 53 is a diagram showing the layered division multiplexed physicallayer pipes with respect to before time-interleaving.

Referring to FIG. 53, one core layer physical layer pipe (PLP #0) andtwo enhanced layer physical layer pipes (PLP #1, PLP #2) are layereddivision multiplexed.

In the case of FIG. 53, the start position and the size of the enhancedlayer physical layer pipes (PLP #1, PLP #2) can be clearly identified.

FIG. 54 is a diagram showing the layered division multiplexed physicallayer pipes with respect to after time-interleaving.

Referring to FIG. 54, the start positions of the enhanced layer physicallayer pipes (PLP #1, PLP #2) are changed by applying time-interleaving(hybrid time interleaving with only twisted block interleaver). In theexample of FIG. 54, the size information of the physical layer pipes andthe start position information of the core layer physical layer pipe(PLP #0) may be not changed after time-interleaving.

When the hybrid time interleaving which corresponds to the convolutionaldelay line with the Variable Bit Rate (VBR) is used, both the startposition information and the size information of the enhanced physicallayer pipe may be changed after the time-interleaving.

For example, when two physical layer pipes (PLP # A, PLP # B) are timedivision multiplexed (TDMed) and the time-interleaving is performed byusing the convolutional delay line with VBR, the size information may bechanged before/after the time interleaving as follows:

-   -   PLP # A: N_(FEC_TI_MAX)=5, N_(r)=8, N_(IU)=2->(time=0;        N_(FEC_TI)=3), (time=1; N_(FEC_TI)=1)    -   PLP # B: N_(FEC_TI_MAX)=4, N_(r)=10, N_(IU)=2->=0;        N_(FEC_TI)=4), (time=1; N_(FEC_TI)=2)    -   time=0        -   Before TI: plp_size(A)=3×8=24, plp_size(B)=4×10=40        -   After TI: plp_size(A)=3×4+1×4=16, plp_size(B)=4×5+1×5=25    -   time=1        -   Before TI: plp_size(A)=1×8=8, plp_size(B)=2×10=20        -   After TI: plp_size(A)=1×4+3×4=16, plp_size(B)=2×5+4×5=30

That is, the size information of the physical layer pipe (PLP # A)before time-interleaving is 3×8=24 because the number of FEC blocks ofthe physical layer pipe (PLP # A) is 3 and the number of cells which areincluded in each FEC block is 8, at the first timing (time=0). The sizeinformation of the physical layer pipe (PLP # B) beforetime-interleaving is 4×10=40 because the number of FEC blocks of thephysical layer pipe (PLP # B) is 4 and the number of cells which areincluded in each FEC block is 10, at the first timing (time=0).

The size information of the physical layer pipe (PLP # A) beforetime-interleaving is 1×8=8 because the number of FEC blocks of thephysical layer pipe (PLP # A) is 1 and the number of cells which areincluded in each FEC block is 8, at the second timing (time=1). The sizeinformation of the physical layer pipe (PLP # B) beforetime-interleaving is 2×10=20 because the number of FEC blocks of thephysical layer pipe (PLP # B) is 2 and the number of cells which areincluded in each FEC block is 10, at the second timing (time=1).

In the example explained above, N_(FEC_TI_MAX), N_(r), N_(IU) andN_(FEC_TI) are as explained earlier. In the example explained above, oneFEC block is divided into two subframes after the time-interleaving tobe transmitted because N_(IU) is 2.

That is, the size information of the physical layer pipe (PLP # A) aftertime-interleaving is (3×(8/2))+(1×(8/2))=16 if it is assumed that theinitial values corresponding to one FEC block are stored in theconvolutional delay line, because the number of FEC blocks of thephysical layer pipe (PLP # A) is 3, the number of cells which areincluded in each FEC block is 8 and the time interleaving unit is 2, atthe first timing (time=0). The size information of the physical layerpipe (PLP # B) after time-interleaving is (4×(10/2))+(1×(10/2))=25 if itis assumed that the initial values corresponding to one FEC block arestored in the convolutional delay line, because the number of FEC blocksof the physical layer pipe (PLP # B) is 4, the number of cells which areincluded in each FEC block is 10 and the time interleaving unit is 2, atthe first timing (time=0). In this case, the start position informationof the physical layer pipe (PLP # A) may be 0 and the start positioninformation of the physical layer pipe (PLP # B) may be 16, which is thesize information of the physical layer pipe (PLP # A) because the TDM isapplied.

The size information of the physical layer pipe (PLP # A) aftertime-interleaving is (1×(8/2))+(3×(8/2))=16 if it is considered thatonly half of the cells of the FEC block corresponding to the firsttiming have been transferred by the previous subframe, because thenumber of FEC blocks of the physical layer pipe (PLP # A) is 1, thenumber of cells which are included in each FEC block is 8 and the timeinterleaving unit is 2, at the second timing (time=1). The sizeinformation of the physical layer pipe (PLP # B) after time-interleavingis (2×(10/2))+(4×(10/2))=30 if it is considered that only half of thecells of the FEC block corresponding to the first timing have beentransferred by the previous subframe, because the number of FEC blocksof the physical layer pipe (PLP # B) is 2, the number of cells which areincluded in each FEC block is 10 and the time interleaving unit is 2, atthe second timing (time=1).

In this case, the amount of data cells mapping to the current subframeare the size information (plp_size) of after time-interleaving.

Therefore, both the start position information and the size informationof the enhanced layer physical layer pipe may be changed when theinter-subframe interleaving with variable bit rate is performed as shownin the example above.

In the example above, the subframe includes 16 active cells of physicallayer pipe (PLP # A) because the size of the physical layer pipe (PLP #A) is 16 and includes 25 active cells of physical layer pipe (PLP # B)because the size of the physical layer pipe (PLP # B) is 25, at thefirst timing (time=0).

If the signaling is performed with respect to before time-interleaving(L1D_plp_size(A)=24, L1D_plp_start(A)=0), the receiver inputs the 16data cells of the physical layer pipe (PLP # A) and 8 data cells of thephysical layer pipe (PLP # B) to the time deinterleaver for decoding thephysical layer pipe (PLP # A) and the decoding is failed. That is, thesignaling has to be performed with respect to after time-interleaving(L1D_plp_size(A)=16, L1D_plp_start(A)=0) so that the decoder inputs 16data cells of the physical layer pipe (PLP # A) to the timedeinterleaver for decoding the physical layer pipe (PLP # A) and thedecoding is performed successfully.

If the signaling is performed with respect to before time-interleaving(L1D_plp_size(B)=40, L1D_plp_start(B)=24), the receiver inputs only 16data cells (24˜40) of the physical layer pipe (PLP # B) to the timedeinterleaver for decoding the physical layer pipe (PLP # B) and thedecoding is failed. That is, the signaling has to be performed withrespect to after time-interleaving (L1D_plp_size(B)=25,L1D_plp_start(B)=16) so that the decoder inputs 25 data cells of thephysical layer pipe (PLP # B) to the time deinterleaver for decoding thephysical layer pipe (PLP # B) and the decoding is performedsuccessfully.

Therefore, the signaling fields (L1D_plp_size, L1D_plp_start) for thecore layer physical layer pipe have to be signaled with respect to aftertime-interleaving.

FIG. 55 is a diagram showing the subframe including layered divisionmultiplexed physical layer pipes.

Referring to FIG. 55, the subframe is composed of one core layerphysical layer pipe (PLP #0) and two enhanced layer physical layer pipe(PLP #1, PLP #2).

The enhanced layer physical layer pipes (PLP #1, PLP #2) may be mixedwith each other in the subframe because the time interleaving is appliedbased on the core layer.

The receiver extracts the subframe from the received signal first andaccesses the core layer data cells in the extracted subframe. On theother hand, the access to the enhanced layer physical layer pipe may beperformed after time-deinterleaving to reduce the receiver's complexitybecause the layered division multiplexing in the transmitter isperformed before time-interleaving.

Therefore, when the layered division multiplexing is applied, since theaccess to the core layer physical layer pipes is performed from thesubframe, it is preferable that the size and the start position of thephysical layer pipe are calculated based on after time-interleaving.Since the access to the enhanced layer physical layer pipes is performedafter time-deinterleaving, it is preferable that the size and the startposition of the physical layer pipe are calculated based on beforetime-interleaving.

FIG. 56 is a diagram showing the first timing of the convolutional delayline performing the time interleaving corresponding to the physicallayer pipes shown in FIGS. 53˜55.

In an example of FIG. 56, the physical layer pipe (PLP #0) is a corelayer physical layer pipe, and corresponds to a case of N_(r)=16,N_(FEC_TI_MAX)=3 and N_(IU)=3. The physical layer pipes (PLP #1, PLP #2)are all enhanced layer physical layer pipes, each of which correspondsto a case of N_(r)=8 (PLP #1) or N_(r)=4 (PLP #2).

When the number of FEC blocks of the physical layer pipe (PLP #0) is 3(N_(FEC_TI)=3), the number of cells corresponding to the core layerphysical layer pipe (PLP #0) may be 3 (N_(FEC_TI))×16 (N_(r))=48 and thenumbers of cells corresponding to the enhanced layer physical layerpipes (PLP #1, PLP #2) corresponding to the core layer physical layerpipe (PLP #0) may be 4 (N_(FEC_TI))×8 (N_(r))=32 and 4 (N_(FEC_TI))×4(N_(r))=16, respectively, at the first timing (Time=0).

Therefore, the output of LDM combining is as shown in the left side ofFIG. 56.

Since the time interleaving unit is 3 (N_(IU)=3), the output (5605) ofLDM combining of three PLPs (PLP #0, PLP #1, PLP #2) may be divided intothree pieces, the first piece (5610) may correspond to the first branchand may become the CDL output which is transferred in the subframecorresponding to the first timing, the second piece (5620) maycorrespond to the second branch and may be stored in one FIFO register,and the third piece (5630) may correspond to the third branch and may bestored in the first FIFO register among two FIFO registers.

In this case, as explained above, the initial values corresponding toone FEC block may be stored in the FIFO registers of the convolutionaldelay line, and each of the FIFO registers may be initialized with thenumber, corresponding to five core layer cells, of initial values.

Together with the first piece (5610) of the output of LDM combining, theinitial values (5650) which are initialized in the FIFO registercorresponding to the second branch of the convolutional delay line andthe initial values (5660) which are initialized in the second FIFOregister among FIFO registers corresponding to the third branch becomethe output of CDL transmitted in the subframe at the first timing.

In this case, the second FIFO register among two FIFO registerscorresponding to the third branch of the convolutional delay line maystore the initial values (5670) which are initialized in the first FIFOregister among the two FIFO registers at the previous timing.

Therefore, if the size information (L1D_plp_size) and the start positioninformation (L1D_plp_start) for the core layer physical layer pipe (PLP#0) are signaled based on after time interleaving at the first timing(Time=0), L1D_plp_size is 18+5+5=28 and L1D_plp_start is 0. Moreover, ifthe size information (L1D_plp_size) and the start position information(L1D_plp_start) for the enhanced layer physical layer pipe (PLP #1) aresignaled based on before time interleaving at the first timing (Time=0),L1D_plp_size is 32 and L1D_plp_start is 0 because the signalinginformation is generated corresponding to the output of LDM combiningbefore applying CDL. Moreover, if the size information (L1D_plp_size)and the start position information (L1D_plp_start) for the enhancedlayer physical layer pipe (PLP #2) are signaled based on before timeinterleaving at the first timing (Time=0), L1D_plp_size is 16 andL1D_plp_start is 32, which is the size information of the physical layerpipe (PLP #1) because the signaling information is generatedcorresponding to the output of LDM combining before applying CDL.

FIG. 57 is a diagram showing the second timing of the convolutionaldelay line performing the time interleaving corresponding to thephysical layer pipes shown in FIGS. 53˜55.

In an example of FIG. 57, the physical layer pipe (PLP #0) is a corelayer physical layer pipe, and corresponds to a case of N_(r)=16,N_(FEC_TI_MAX)=3 and N_(IU)=3. The physical layer pipes (PLP #1, PLP #2)are all enhanced layer physical layer pipes, each of which correspondsto a case of N_(r)=8 (PLP #1) or N_(r)=4 (PLP #2).

When the number of FEC blocks of the physical layer pipe (PLP #0) is 2(N_(FEC_TI)=2), the number of cells corresponding to the core layerphysical layer pipe (PLP #0) may be 2 (N_(FEC_TI))×16 (N_(r))=32 and thenumbers of cells corresponding to the enhanced layer physical layerpipes (PLP #1, PLP #2) corresponding to the core layer physical layerpipe (PLP #0) may be 24 and 8, respectively, at the second timing(Time=1).

Therefore, the output of LDM combining is as shown in the left side ofFIG. 57.

Since the time interleaving unit is 3 (N_(IU)=3), the output (5705) ofLDM combining of three PLPs (PLP #0, PLP #1, PLP #2) may be divided intothree pieces, the first piece (5710) may correspond to the first branchand may become the CDL output which is transferred in the subframecorresponding to the second timing, the second piece (5720) maycorrespond to the second branch and may be stored in one FIFO register,and the third piece (5730) may correspond to the third branch and may bestored in the first FIFO register among two FIFO registers.

Together with the first piece (5710) of the output of LDM combining atthe second timing, the second piece (5620) of the first timing which isstored in the FIFO register corresponding to the second branch of theconvolutional delay line at the previous timing and the initial values(the number of initial values corresponding to five core layer cells)(5670) which are stored in the second FIFO register among FIFO registerscorresponding to the third branch at the previous timing become theoutput of CDL transmitted in the subframe.

In this case, the second FIFO register among two FIFO registerscorresponding to the third branch of the convolutional delay line maystore the third piece (5630) of the first timing which is stored in thefirst FIFO register among the two FIFO registers at the previous timing.

Therefore, if the size information (L1D_plp_size) and the start positioninformation (L1D_plp_start) for the core layer physical layer pipe (PLP#0) are signaled based on after time interleaving at the second timing(Time=1), L1D_plp_size is 12+15+5=32 and L1D_plp_start is 0. Moreover,if the size information (L1D_plp_size) and the start positioninformation (L1D_plp_start) for the enhanced layer physical layer pipe(PLP #1) are signaled based on before time interleaving at the secondtiming (Time=1), L1D_plp_size is 24 and L1D_plp_start is 0 because thesignaling information is generated corresponding to the output of LDMcombining before applying CDL. Moreover, if the size information(L1D_plp_size) and the start position information (L1D_plp_start) forthe enhanced layer physical layer pipe (PLP #2) are signaled based onbefore time interleaving at the second timing (Time=1), L1D_plp_size is8 and L1D_plp_start is 24, which is the size information of the physicallayer pipe (PLP #1) because the signaling information is generatedcorresponding to the output of LDM combining before applying CDL.

FIG. 58 is a diagram showing the third timing of the convolutional delayline performing the time interleaving corresponding to the physicallayer pipes shown in FIGS. 53˜55.

In an example of FIG. 58, the physical layer pipe (PLP #0) is a corelayer physical layer pipe, and corresponds to a case of N_(r)=16,N_(FEC_TI_MAX)=3 and N_(IU)=3. The physical layer pipes (PLP #1, PLP #2)are all enhanced layer physical layer pipes, each of which correspondsto a case of N_(r)=8 (PLP #1) or N_(r)=4 (PLP #2).

When the number of FEC blocks of the physical layer pipe (PLP #0) is 1(N_(FEC_TI)=1), the number of cells corresponding to the core layerphysical layer pipe (PLP #0) may be 1 (N_(FEC_TI))×16 (N_(r))=16 and thenumbers of cells corresponding to the enhanced layer physical layerpipes (PLP #1, PLP #2) corresponding to the core layer physical layerpipe (PLP #0) may be 8 and 8, respectively, at the third timing(Time=2).

Therefore, the output of LDM combining is as shown in the left side ofFIG. 58.

Since the time interleaving unit is 3 (N_(IU)=3), the output (5805) ofLDM combining of three PLPs (PLP #0, PLP #1, PLP #2) may be divided intothree pieces, the first piece (5810) may correspond to the first branchand may become the CDL output which is transferred in the subframecorresponding to the third timing, the second piece (5820) maycorrespond to the second branch and may be stored in one FIFO register,and the third piece (5830) may correspond to the third branch and may bestored in the first FIFO register among two FIFO registers.

Together with the first piece (5810) of the output of LDM combining atthe third timing, the second piece (5720) of the second timing which isstored in the FIFO register corresponding to the second branch of theconvolutional delay line at the previous timing and the third piece(5630) of the first timing which is stored in the second FIFO registeramong FIFO registers corresponding to the third branch at the previoustiming become the output of CDL transmitted in the subframe.

In this case, the second FIFO register among two FIFO registerscorresponding to the third branch of the convolutional delay line maystore the third piece (5730) of the second timing which is stored in thefirst FIFO register among the two FIFO registers at the previous timing.

Therefore, if the size information (L1D_plp_size) and the start positioninformation (L1D_plp_start) for the core layer physical layer pipe (PLP#0) are signaled based on after time interleaving at the third timing(Time=2), L1D_plp_size is 6+10+15=31 and L1D_plp_start is 0. Moreover,if the size information (L1D_plp_size) and the start positioninformation (L1D_plp_start) for the enhanced layer physical layer pipe(PLP #1) are signaled based on before time interleaving at the thirdtiming (Time=2), L1D_plp_size is 8 and L1D_plp_start is 0 because thesignaling information is generated corresponding to the output of LDMcombining before applying CDL. Moreover, if the size information(L1D_plp_size) and the start position information (L1D_plp_start) forthe enhanced layer physical layer pipe (PLP #2) are signaled based onbefore time interleaving at the third timing (Time=2), L1D_plp_size is 8and L1D_plp_start is 8, which is the size information of the physicallayer pipe (PLP #1) because the signaling information is generatedcorresponding to the output of LDM combining before applying CDL.

FIG. 59 is a diagram showing the first timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55.

In an example of FIG. 59, the receiver may recognize that the number ofFEC blocks corresponding to the core layer physical layer pipe (PLP #0)at the first timing (Time=0) is 3 (the number of FEC blocks initializedat the previous timing is 1, the number of FEC blocks initialized at theprevious-previous timing is 1) by signaling the information such asN_(FEC_TI)=[3 1 1] for the core layer physical layer pipe (PLP #0).

The output of the convolutional delay line shown in FIG. 56 may bereceived as an input of the inverse convolutional delay line shown inthe left side of FIG. 59.

The received data is divided into three pieces, the first piece (5910)is stored in the first FIFO register among two FIFO registerscorresponding to the first branch of the inverse convolutional delayline, the second piece (5920; initial values) is stored in the FIFOregister corresponding to the second branch of the inverse convolutionaldelay line, the third piece (5930; initial values) corresponds to thethird branch of the inverse convolutional delay line and is output asthe time deinterleaver output.

In this case, 28 cells may be extracted from the received data for usingthe cells as the input of the inverse convolutional delay line becauseL1D_plp_size=28 and L1D_plp_start=0 are signaled with respect to aftertime-interleaving for the core layer physical layer pipe (PLP #0). Inthis case, the data cells corresponding to three FEC blocks are writtento the first branch, the data cells corresponding to one FEC block arewritten to the second branch and the data cells corresponding to one FECblock are written to the third branch among 28 cells, according toN_(FEC_TI)=[3 1 1].

In this case, each of the FIFO registers of the inverse convolutionaldelay line may be initialized with the initial values, the number of theinitial values corresponds to five core layer cells. In this case, theFIFO register corresponding to the first branch may be initialized withsix initial values and the FIFO registers corresponding to remainingbranches may be initialized with five initial values (N_(r)=16).

Together with the third piece of the received data, the initial values(5950) which are initialized in the second FIFO register among two FIFOregisters corresponding to the first branch of the inverse convolutionaldelay line at the previous timing and the initial values (5960) whichare initialized in the FIFO register corresponding to the second branchat the previous timing become the output of the time deinterleaver atthe first timing.

In this case, the second FIFO register among two FIFO registerscorresponding to the first branch of the inverse convolutional delayline may store the initial values (5970) which are initialized in thefirst FIFO register among the two FIFO registers at the previous timing.

Therefore, the data of physical layer pipe (PLP #0) are not output asthe output of the time deinterleaver at the first timing.

FIG. 60 is a diagram showing the second timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55.

In an example of FIG. 60, the receiver may recognize that the number ofFEC blocks corresponding to the core layer physical layer pipe (PLP #0)at the second timing (Time=1) is 2 (the number of FEC blockscorresponding to the core layer physical layer pipe at the previoustiming is 3, the number of FEC blocks initialized at theprevious-previous timing is 1) by signaling the information such asN_(FEC_TI)=[2 3 1] for the core layer physical layer pipe (PLP #0).

The output of the convolutional delay line shown in FIG. 57 may bereceived as an input of the inverse convolutional delay line shown inthe left side of FIG. 60.

The received data is divided into three pieces, the first piece (6010)is stored in the first FIFO register among two FIFO registerscorresponding to the first branch of the inverse convolutional delayline, the second piece (6020) is stored in the FIFO registercorresponding to the second branch of the inverse convolutional delayline, the third piece (6030; initial values) corresponds to the thirdbranch of the inverse convolutional delay line and is output as the timedeinterleaver output.

In this case, 32 cells may be extracted from the received data for usingthe cells as the input of the inverse convolutional delay line becauseL1D_plp_size=32 and L1D_plp_start=0 are signaled with respect to aftertime-interleaving for the core layer physical layer pipe (PLP #0). Inthis case, the data cells corresponding to two FEC blocks are written tothe first branch, the data cells corresponding to three FEC block arewritten to the second branch and the data cells corresponding to one FECblock are written to the third branch among 32 cells, according toN_(FEC_TI)=[2 3 1].

In this case, the second FIFO register among two FIFO registerscorresponding to the first branch may store the first piece (5910) ofthe data received at the first timing which is stored in the first FIFOregister at the first timing.

Together with the third piece (6030) of the received data, the initialvalues (5970) which are stored in the second FIFO register among twoFIFO registers corresponding to the first branch of the inverseconvolutional delay line at the first timing and the initial values(5920) which are initialized in the FIFO register corresponding to thesecond branch become the output of the time deinterleaver at the secondtiming.

Therefore, the data of physical layer pipe (PLP #0) are not output asthe output of the time deinterleaver at the second timing.

FIG. 61 is a diagram showing the third timing of the inverseconvolutional delay line performing the time deinterleavingcorresponding to the physical layer pipes shown in FIGS. 53˜55.

In an example of FIG. 61, the receiver may recognize that the number ofFEC blocks corresponding to the core layer physical layer pipe (PLP #0)at the third timing (Time=2) is 1 (the number of FEC blockscorresponding to the core layer physical layer pipe at the previoustiming is 2, the number of FEC blocks corresponding to the core layerphysical layer pipe at the previous-previous timing is 3) by signalingthe information such as N_(FEC_TI)=[1 2 3] for the core layer physicallayer pipe (PLP #0).

The output of the convolutional delay line shown in FIG. 58 may bereceived as an input of the inverse convolutional delay line shown inthe left side of FIG. 61.

The received data is divided into three pieces, the first piece (6110)is stored in the first FIFO register among two FIFO registerscorresponding to the first branch of the inverse convolutional delayline, the second piece (6120) is stored in the FIFO registercorresponding to the second branch of the inverse convolutional delayline, the third piece (6130) corresponds to the third branch of theinverse convolutional delay line and is output as the time deinterleaveroutput.

In this case, 31 cells may be extracted from the received data for usingthe cells as the input of the inverse convolutional delay line becauseL1D_plp_size=31 and L1D_plp_start=0 are signaled with respect to aftertime-interleaving for the core layer physical layer pipe (PLP #0). Inthis case, the data cells corresponding to one FEC block are written tothe first branch, the data cells corresponding to two FEC blocks arewritten to the second branch and the data cells corresponding to threeFEC blocks are written to the third branch among 31 cells, according toN_(FEC_TI)=[1 2 3].

In this case, the second FIFO register among two FIFO registerscorresponding to the first branch may store the first piece (6010) ofthe data received at the second timing which is stored in the first FIFOregister at the second timing.

Together with the third piece (6130) of the data received at the thirdtiming, the first piece (5910) of the data received at the first timingwhich is stored in the second FIFO register among two FIFO registerscorresponding to the first branch of the inverse convolutional delayline at the second timing and the second piece (6020) of the datareceived at the second timing which is stored in the FIFO registercorresponding to the second branch become the output of the timedeinterleaver at the third timing.

Therefore, 48 cells of the core layer physical layer pipe (PLP #0), 32cells of the enhanced layer physical layer pipe (PLP #1) and 16 cells ofthe enhanced layer physical layer pipe (PLP #2) are output as the outputof the time deinterleaver at the third timing.

That is, the complete time interleaving block including three FEC blocksis output at the third timing. It can be seen that 48 (16×3) data cellsof the core layer physical layer pipe are output at this timing becauseone FEC block is composed of 16 data cells.

In this case, the cells related to the enhanced layer physical layerpipe (PLP #1) may be identified efficiently from the time-deinterleavedoutput because L1D_plp_size=32 and L1D_plp_start=0 are signaled for theenhanced layer physical layer pipe (PLP #1) based on after timeinterleaving.

In this case, the cells related to the enhanced layer physical layerpipe (PLP #2) may be identified efficiently from the time deinterleavedoutput because L1D_plp_size=16 and L1D_plp_start=32 are signaled for theenhanced layer physical layer pipe (PLP #2) based on after the timeinterleaving.

When LDM is used, an injection level of the enhanced layer physicallayer pipe may be signaled by a field of L1D_plp_ldm_injection_level todetermine its power level relative to associated core layer physicallayer pipe(s). In this case, the injection level of the enhanced layerphysical layer pipe(s) may be varied from 0 dB to 25 dB below associatedcore layer physical layer pipe(s).

In this case, a low injection level of an enhanced physical layer pipeimplies that the transmitting power of the enhanced physical layer pipeincreases. However, this enhanced physical layer pipe signal becomesadditional noise to the associated core layer physical layer pipe(s),which will impact the performance of the core layer physical layerpipe(s).

On the other hand, a high injection level implies less transmittingpower allocated to an enhanced layer physical layer pipe whereasrelatively more robustness of the associated core layer physical layerpipe(s).

In this case, the total power after the injection of the enhancedphysical layer pipe may be normalized to be equal to the power of asingle PLP configuration. In this case, the required SNR of the core andenhanced layer physical layer pipes after LDM combining may depend onthe required SNR of core and enhanced physical layer pipes before LDMcombining as well as the injection level. In this case, the required SNRmay be the minimum value of SNR for the corresponding physical layerpipe to be properly transmitted/received.

The required SNR of core layer physical layer pipe (SNR_(CL_AC)) and therequired SNR of enhanced layer physical layer pipe (SNR_(EL_AC)) afterLDM combining may be determined as Equations 8 and 9.

$\begin{matrix}{{SNR}_{CL\_ AC} = {{SNR}_{CL\_ BC} + {10\; {\log_{10}\left( {1 + 10^{\frac{- {IL}}{10}}} \right)}} - {10\; {\log_{10}\left( {1 - 10^{\frac{{SNR}_{CL\_ BC} - {IL}}{10}}} \right)}}}} & (8) \\{\mspace{79mu} {{SNR}_{E{L\_ AC}} = {{SNR}_{E{L\_ BC}} + {10\; {\log_{10}\left( {1 + 10^{\frac{IL}{10}}} \right)}}}}} & (9)\end{matrix}$

Here, IL is the injection level in dB scale, SNR_(CL_BC) is the requiredSNR value in dB of the physical layer pipe that is assigned to the corelayer (the required SNR before LDM combining), SNR_(EL_BC) is therequired SNR value in dB of the physical layer pipe that is assigned tothe enhanced layer (the required SNR value before LDM combining). Whenmultiple enhanced layer physical layer pipes are associated with onecore layer physical layer pipe, the same value of injection level may beused for all of those multiple enhanced layer physical layer pipes.Therefore, there may be no multiple values of required SNRs for a corelayer physical layer pipe.

When the injection level of an enhanced physical layer pipe is chosen,it may be important to consider the required SNR of core physical layerpipe(s) before LDM combining. Since the injected enhanced layer physicallayer pipe acts as additional noise to the associated core layerphysical layer pipe(s), the core layer physical layer pipe(s) may not bedecodable if the injection level is less than the required SNR of corelayer physical layer pipe(s) before LDM combing. Furthermore, even ifthe injection level is slightly higher (e.g., 1 dB) than the requiredSNR of core layer physical layer pipe(s) before LDM combining, there maybe still an effect on the SNR performance of the core layer physicallayer pipe(s) after LDM combining. Therefore, in order to provide enoughheadroom between the threshold of required SNR of core layer physicallayer pipe(s) and the injection level, the injection level (IL) ofenhanced layer physical layer pipe(s) may be chosen according toEquation 10.

IL≥SNR_(CL_BC)+3  (10)

In this case, when multiple core layer physical layer pipes areassociated with an enhanced layer physical layer pipe, the least robustcore layer physical layer pipe may be used to choose the condition ofthe injection level.

Particular care may be needed to choose a modulation/code rate (ModCod)combination for the core layer depending on the injection levels of theenhanced layer. In this case, a core layer physical layer pipe may beconfigured with QPSK, 16 QAM, or 64 QAM constellations desirably. When64 QAM is used for a core layer physical layer pipe, the code rate nohigher than 7/15 may be used to avoid high required SNRs in the corelayer desirably.

When a complete delivered product is assembled and delivered by multiplephysical layer pipes, those multiple physical layer pipes are requiredto be simultaneously recovered in ATSC 3.0 receivers, and therefore themaximum number of physical layer pipes required to assemble a completedelivered product may be limited to four, while also satisfying thecondition of the maximum TI memory size of receivers, i.e., 2¹⁹ cells.

Depending on broadcaster's intended services, a complete deliveredproduct carried by multiple physical layer pipes may contain a number ofdifferent data streams such as signaling, multiple audios, video,enhanced video, or application data. Care should be taken when suchmultiple data streams requiring simultaneous recovery in receivers(complete delivered product) are carried in multiple physical layerpipes. In principle, additional physical layer pipe(s) are required whendifferent robustness levels and different coverage areas are intended bybroadcasters. If multiple data streams are required to have the samerobustness level and the same coverage area (e.g., multiple audiostreams in multiple languages), it is preferable that these data streamsbe carried in the same physical layer pipe. In this case, multiplexingthese multiple data streams prior to the physical layer may even bebeneficial due to the statistical multiplexing gain as long as the samerobustness for those multiple data streams is intended. Therefore, whenall of the components of a transmitted product are carried by multiplephysical layer pipes, the maximum number of physical layer pipes forthat product may be limited to four at the transmitter, and those fourphysical layer pipes may consume the full TI memory size (2¹⁹ cells) inorder to maximize the time diversity of individual physical layer pipes.It is not desirable that all of the components of a transmitted productbe carried by more than four physical layer pipes at the transmitter,even though a 4-PLP subset within the complete delivered product of morethan four physical layer pipes would meet the TI memory requirement atreceivers.

The IP-level signaling information such as Low Level Signaling (LLS),including Service List Table (SLT) and Service Layer Signaling (SLS),and Link Mapping Table (LMT) may be configured in a separate physicallayer pipe in order to provide different robustness for the signalinginformation. In such cases, the IP-level signaling information may bepresent in the most robust physical layer pipe out of multiple physicallayer pipes carrying a complete delivered product. When LDM is used, theIP-level signaling information may be present in the most robust corelayer physical layer pipe out of multiple physical layer pipes carryinga complete delivered product.

A complete delivered product that may be composed of one or morephysical layer pipes may contain the appropriate IP-level signalinginformation including LLS and LMT. In this case, the minimum requirementof the LLS and LMT delivery is to be repeated in every 5 seconds. Forfast service acquisition, the LLS and LMT may be sent in every physicallayer frame. This may result in setting L1B_lls_flag=1 (for LLS carriedin the current frame) and L1D_plp_lls_flag=1 (for LLS carried in thecorresponding PLP) in every frame.

When a complete delivered product is carried by multiple physical layerpipes, a possible configuration may be to use multiple subframes. Oneexample of such a service scenario is a robust audio service deliveredin an 8K or 16K FFT subframe and a video service delivered in a 32K FFTsubframe. Therefore, ATSC 3.0 receivers may be able to simultaneouslyrecover multiple subframes that may carry a complete delivered product.In such cases, the CTI mode may not be allowed since the CTI mode isused when a complete delivered product is composed of only a single corelayer physical layer pipe with constant cell rate.

When LDM is used, multiple physical layer pipes that are layereddivision multiplexed may share the common subframe parameters such asFFT size, pilot pattern, and guard interval. Therefore, a completedelivered product may not be delivered by multiple subframes that areall LDM configured, so that receivers do not need simultaneous recoveryof multiple LDM configured subframes.

LDM (Layered Division Multiplexing) may be combined with TDM and/or FDMconfigurations in order to configure multiple physical layer pipeswithin a subframe. When LDM is configured with more than 2 physicallayer pipes, it may be formed as one of the configurations such asLayered Time Division Multiplexing (LTDM), Time Layered DivisionMultiplexing (TLDM), Layered Frequency Division Multiplexing (LFDM), orFrequency Layered Division Multiplexing (FLDM).

In this case, LTDM may correspond to performing time division afterperforming layered division, TLDM may correspond to performing layereddivision after performing time division, LFDM may correspond toperforming frequency division after performing layered division, andFLDM may correspond to performing layered division after performingfrequency division.

For the implementation to have low complexity and low memory use, thetime interleaver block including the memory may be shared by both coreand enhanced physical layer pipes.

In this case, FLDM or LFDM configurations may be regarded as specialcases of TLDM or LTDM respectively, by subslicing dispersed core layerphysical layer pipes. Hereafter, the example of using up to 4 physicallayer pipes configuring a complete delivered product for simultaneousrecovery in receivers will be described.

L1D_plp_start and L1D_plp_size are the signaling fields that determinethe position and placement of each physical layer pipe within asubframe. Regardless of the use of LDM, these signaling fields of corelayer physical layer pipe(s) may be defined with respect to after timeinterleaving (CTI or HTI) and framing. However, when LDM is used,L1D_plp_start and

L1D_plp_size of enhanced layer physical layer pipe(s) may be definedwith respect to before time interleaving because the LDM combining isperformed after constellation mapping and before time interleaving.

FIG. 62 is a diagram showing signaling definitions of L1D_plp_start andL1D_plp_size.

Referring to FIG. 62, the cells indicated by the signaling fields ofenhanced physical layer pipes are spread over a subframe after timeinterleaving, which may not be meaningful information at the framingstage.

In receivers, enhanced physical layer pipes decoded after timede-interleaving and cancellation of core layer physical layer pipe maybe recovered based on the corresponding L1D_plp_start and L1D_plp_sizeof the enhanced physical layer pipes in L1-Detail.

When LDM is configured with multiple core physical layer pipes, eachcore layer physical layer pipe represents a time interleaving group (TIgroup).

FIG. 63 is a diagram showing the time interleaving group assignment formultiple core physical layer pipes.

Referring to FIG. 63, each of three core layer physical layer pipesrepresents one time interleaving group.

These time interleaving groups may be implicitly indexed in ascendingorder according to the order in which the corresponding core layerphysical layer pipes appear within the L1-Detail control signaling. Forthe efficient use of receiver memory, the core layer physical layerpipes for each subframe may be arranged within that subframe inascending order. That is, L1D_plp_start of the first core layer physicallayer pipe in a subframe's L1-Detail control signaling indexed asTI_Group_0 may have the lowest cell index of the L1D_plp_start valuesfor all core layer physical layer pipes within that subframe. Further,L1D_plp_start of the second core layer physical layer pipe in thatsubframe's L1-Detail control signaling indexed as TI_Group_1 may belarger than that of the first core layer physical layer pipe(TI_Group_0) and smaller than that of the third core layer physicallayer pipe (TI_Group_2). In this case, L1D_plp id of each physical layerpipe is independent of the TI_Group values, so that it may not benecessary for L1D_plp id values to be arranged in ascending order withinthe L1-Detail control signaling as in FIG. 63.

FIG. 64 is a diagram showing two enhanced layer physical layer pipeswhich are injected into a single core layer physical layer pipe.

Referring to FIG. 64, when multiple enhanced layer physical layer pipesare associated with a single core layer physical layer pipe (e.g.,L1D_plp_id_0), those enhanced layer physical layer pipe may all have thesame LDM injection level as signaled by L1D_plp_ldm_injection_level. Ifthose enhanced layer physical layer pipes have different injectionlevels, the portions of the core layer physical layer pipe associatedwith these two enhanced layer physical layer pipes (e.g., L1D_plp_id_0)may have different robustness, which will eventually provide differentcoverage areas for a single content.

When enhanced layer physical layer pipe(s) are positioned and associatedwith core layer physical layer pipe(s) within a subframe, L1D_plp_startand L1D_plp_size of enhanced layer physical layer pipe(s) may becarefully determined such that cells of enhanced physical layer pipe(s)are continuously associated with the cells of core layer physical layerpipe(s).

FIG. 65 is a diagram showing an example of undesirable LDMconfiguration.

Referring to FIG. 65, L1D_plp_start of the enhanced layer physical layerpipe (L1D_plp_id_1) is not the same as that of the core layer physicallayer pipe (L1D_plp_id_0). In this case, portions of the core layerphysical layer pipe will have different robustness, and therefore, sucha configuration may not be preferable. Furthermore, L1D_plp_size of theenhanced layer physical layer pipe may be required not to be eithershorter or longer than the core layer physical layer pipe. When the HTI(Hybrid Time Interleaving) mode is used, all the physical layer pipesconfigured by the HTI mode may use integer numbers of FEC blocks. Insuch cases, the number of actual data cells in the enhanced layer may beset to be less than or equal to those in the core layer, and enhancedlayer dummy modulation values may be used when necessary.

FIG. 66 is a diagram showing another example of undesirable LDMconfiguration.

Referring to FIG. 66, there is a duration in which the layered divisionmultiplexing is not applied in the core layer physical layer pipe(L1D_plp_id_0).

When multiple physical layer pipes are configured in the enhanced layer,L1D_plp_start of the following enhanced layer physical layer pipe in asubframe (L1D_plp_start_3) may correspond to the immediately followingcell of the preceding enhanced layer physical layer pipe (L1D_plp_id_2),to prevent gaps between enhanced layer physical layer pipes.

The CTI (Convolutional Time Interleaving) mode may be used when acomplete delivered product consists of a single core layer physicallayer pipe that has a constant cell rate. For example, a case where onecore layer physical layer pipe and one enhanced layer physical layerpipe have the same L1D_plp_start and L1D_plp_size with a constant cellrate may be a representative example of the CTI mode. When the CTI modeis used, it is not necessary to achieve an integer number of FEC blocksper subframe so it is therefore desirable that the data cells in boththe core and enhanced layers be completely filled in a subframe.

FIG. 67 is a diagram showing an example of allowed LDM configuration inthe CTI mode.

Referring to FIG. 67, when a subframe consists of multiple core layerphysical layer pipes (multiple TI groups) representing differentdelivered products, each physical layer pipe within that subframe shouldhave a constant cell rate to be configured with the CTI mode.Furthermore, any enhanced layer physical layer pipes associated withcore layer physical layer pipes should not be spread over multiple timeinterleaving groups. In the CTI mode, an incomplete FEC block at thelast part of a core layer physical layer pipe is time interleaved and itshould be buffered until the next subframe to be decoded in a receiver.In such a case, the FEC block of the enhanced layer physical layer pipeassociated with that incomplete FEC block of the core layer physicallayer pipe should be also buffered until the next subframe. This impliesthat when an enhanced layer physical layer pipe is spread over multipletime interleaving groups, any subsequent FEC blocks of that enhancedlayer physical layer pipe associated with the following timeinterleaving group(s) should be buffered as well, which may consume alarge amount of memory in a receiver. Due to this reason, the exampleLDM configuration shown in FIG. 63 and FIG. 64, in which an enhancedlayer physical layer pipe is spread over multiple TI groups, may not beallowed when the CTI is used. In the CTI mode, when an LDM configurationas shown in FIG. 67 is used, building a complete delivered productcomposed of physical layer pipes belonging to different timeinterleaving groups may not be allowed. A complete delivered product mayhave to be composed of the core and enhanced layer physical layer pipeswithin the same time interleaving group when the CTI mode is used.

FIG. 68 is a diagram showing another example of allowed LDMconfiguration in the CTI mode.

Referring to FIG. 68, a core layer physical layer pipe that isassociated with multiple enhanced layer physical layer pipes may beconfigured with a single CTI. When such a configuration is used, each ofthe enhanced layer physical layer pipes associated with the core layerphysical layer pipe may have a constant cell rate. This implies thatL1D_plp_start and L1D_plp_size of each enhanced layer physical layerpipe remain constant from one subframe to the next subframe, so thatreceivers do not need to track these signaling values of the previoussubframe.

When the HTI (Hybrid Time Interleaving) mode is used, each of the coreand enhanced layer physical layer pipes is composed of an integer numberof FEC blocks, and therefore, the case that an enhanced layer physicallayer pipe is spread over multiple time interleaving groups can beimplemented without further receiver memory requirement.

FIG. 69 is a diagram showing an example of allowed LDM configuration inthe HTI mode.

Referring to FIG. 69, two core layer physical layer pipes are associatedwith an enhanced layer physical layer pipe in the HTI mode. The 4-PLPconfiguration as shown in FIG. 63 and FIG. 64 where an enhanced layerphysical layer pipe is spread over multiple time interleaving groups,may be allowed by the HTI mode. In this case, using different timeinterleaving mode for different time interleaving group associated withthe same enhanced physical layer pipe may be not allowed. When the HTImode is used in those cases that the same enhanced layer physical layerpipe is spread over multiple time interleaving groups, the use of theConvolutional Delay Line (CDL) may not be allowed. If the ConvolutionalDelay Line were used, the two core layer physical layer pipes might havedifferent interleaving depths over multiple subframes, and therefore,the portions of the single enhanced layer physical layer pipe associatedwith those two core layer physical layer pipes might have differentdecoding times, which eventually would require a large amount of memoryin receivers.

Since the HTI mode requires an integer number of FEC blocks for eachphysical layer pipe, the total number of cells of the core layerphysical layer pipe(s) may be different from that of the enhanced layerphysical layer pipe(s) depending on the modulation/code rate (ModCod)combination choice for each physical layer pipe. In such cases, enhancedlayer dummy modulation values may be used, so that the core layer andthe enhanced layer have the same number of cells. In this case, theseenhanced layer dummy modulation values may be inserted after the lastenhanced layer physical layer pipe in a PLP group. Furthermore, thesedummy modulation values may have the same constellation mapping andinjection level as the preceding enhanced layer physical layer pipe, sothat the core layer physical layer pipe associated with the precedingenhanced layer physical layer pipe and the dummy modulation values has auniform robustness.

When an enhanced layer physical layer pipe is spread over multiple timeinterleaving groups (HTI-based LTDM or LFDM configurations), an extraframe buffer may be needed when the time interleaving depth of corelayer physical layer pipes belonging to multiple time interleavinggroups are substantially different. For example, if the timeinterleaving depth of the first core layer physical layer pipe is largerthan that of the second core layer physical layer pipe, the portion ofthe enhanced physical layer pipe associated with the second core layerphysical layer pipe may have to be buffered due to the large timeinterleaving depth of the first core layer physical layer pipe. In thiscase, for buffering such a portion of the enhanced layer physical layerpipe, an extra frame buffer (e.g., DRAM) may be used, rather thanconsuming the time interleaving memory (e.g., SRAM). In order to avoidthe extra frame buffer for enhanced layer physical layer pipe, multiplecore layer physical layer pipes associated with an enhanced layerphysical layer pipe may use the same or similar time interleaving depth.This can be achieved when the number of FEC blocks per time interleavingblock is the same or similar for the multiple core layer physical layerpipes associated with an enhanced layer physical layer pipe.

FIG. 70 is a diagram showing an example of use of time interleavingblocks for HTI-based LTDM or LFDM configurations.

Referring to FIG. 70, multiple core layer physical layer pipesassociated with an enhanced layer physical layer pipe use the same orsimilar (the differences are less than a predetermined threshold value)time interleaving block size.

The use of the same or similar time interleaving block size is not onlyfor avoiding extra frame memory, but also for providing the sameperformance for a single enhanced layer physical layer pipe.

The no time interleaving mode (no TI mode) may be used regardless of theuse of LDM. When the no time interleaving mode is used and an enhancedlayer physical layer pipe is spread over multiple time interleavinggroups, the core layer physical layer pipes associated with thatenhanced layer physical layer pipe may have to have integer number ofFEC blocks.

FDM, which is enabled by cell multiplexing, may be combined with LDMsuch as FLDM or LFDM configurations. In this case, the cell multiplexingcontrolled by physical layer type information (L1D_plp_type), physicallayer pipe subslice interval information (L1D_plp_subslice_interval) andphysical layer pipe subslice number information (L1D_plp_num_subslices)may be applied with respect to core layer physical layer pipe(s) only.In this case, all the physical layer pipe type information(L1D_plp_type), the physical layer pipe subslice interval information(L1D_plp_subslice_interval) and the physical layer pipe subslice numberinformation (L1D_plp_num_subslices) may be signaled only for core layerphysical layer pipe(s) and may not be signaled for enhanced layerphysical layer pipe(s).

The physical layer pipe type information (L1D_plp_type) may be foridentifying any one of the first type corresponding to a non-dispersedphysical layer pipe or the second type corresponding to a dispersedphysical layer pipe.

The physical layer pipe subslice interval information(L1D_plp_subslice_interval) may only be signaled when L1D_plp_type=1(dispersed physical layer pipe), and may be set equal to the number ofsequentially-indexed data cells measured from the beginning of asubslice for a physical layer pipe to the beginning of the next subslicefor the same physical layer pipe.

For example, if L1D_plp_start=100 and L1D_plp_subslice_interval=250,then the first data cell of the first subslice of the current physicallayer pipe would be located at index 100, and the first data cell of thesecond subslice of the current physical layer pipe would be located atindex 100+250=350.

The physical layer pipe subslice number information(L1D_plp_num_subslices) may only be signaled when L1D_plp_type=1(dispersed physical layer pipe), and may be set equal to one less thanthe actual number of subslices used for the current physical layer pipewithin the current subframe.

FIG. 71 is a diagram showing an example of FLDM configuration.

Referring to FIG. 71, an FLDM configuration may be relatively simplebecause core and enhanced layer physical layer pipes corresponding tothe FDM cells have the same number of cells. When the cell multiplexingfor FDM is applied, dummy modulation values may be required because thedefined subslice interval (L1D_plp_subslice_interval) may not be aninteger multiple of the total number of data cells. In this case, thecell multiplexing of FDM may not be applied to the data part of thePreamble and SBS.

Another type of FDM combination with LDM is an LFDM configuration.

FIG. 72 is a diagram showing an example of LFDM configuration.

Referring to FIG. 72, since the subslicing parameters are only appliedto core layer physical layer pipes, the cell writing order of theassociated enhanced layer physical layer pipes may follow the cellwriting order of those core layer physical layer pipes. When the cellmultiplexing for FDM requires a physical layer pipe to span the wholesubframe duration, receivers may also need to buffer enhanced layerphysical layer pipe(s) for the whole subframe duration because theenhanced layer physical layer pipe(s) that follow the cell writing orderof core layer physical layer pipe(s) should be re-ordered. In this case,for buffering the enhanced layer physical layer pipe(s), an extra framebuffer (e.g., DRAM) may be used, rather than consuming the TI memory(e.g., SRAM). Due to this additional frame memory requirement, thenumber of cells of enhanced layer physical layer pipe(s) buffered in aframe memory may be less than or equal to 2²⁰ when such an LFDMconfiguration is used. That is, in the example of FIG. 72, the sum ofL1D_plp_size of PLP #0 and PLP #1 in the core layer (which is equal tothe sum of L1D_plp_size of PLP #2 and PLP #3 in the enhanced layer) maynot exceed 2²⁰ cells due to the limitation of frame buffer in receivers.

In the example of FIG. 72, the enhanced layer physical layer pipe (PLP#3) is spread over multiple TI groups, and therefore the CTI mode may bedisallowed.

As described above, the apparatus and method for generating broadcastsignal frame according to the present invention are not limited to theconfigurations and methods of the aforementioned embodiments, but someor all of the embodiments may be selectively combined such that theembodiments are modified in various manners.

1. An apparatus for generating broadcast signal frame, comprising: acombiner configured to generate a multiplexed signal by combining a corelayer signal and an enhanced layer signal; a power normalizer configuredto reduce power of the multiplexed signal to a power level correspondingto the core layer signal; a time interleaver configured to generate atime-interleaved signal by performing time-interleaving that is appliedto both the core layer signal and the enhanced layer signal; and a framebuilder configured to generate a broadcast signal frame including apreamble for signaling start position information and size informationfor each of Physical Layer Pipes (PLPs), wherein the Physical LayerPipes include a core layer physical layer pipe corresponding to the corelayer signal and an enhanced layer physical layer pipe corresponding tothe enhanced layer signal, and injection level information correspondingto the enhanced layer signal is signaled corresponding to the enhancedlayer physical layer pipe.
 2. The apparatus of claim 1, wherein thePhysical Layer Pipes includes two or more enhanced layer physical layerpipes and the two or more enhanced layer physical layer pipes have thesame injection level information when the core layer physical layer pipeis layered division multiplexed with the two or more enhanced layerphysical layer pipes.
 3. The apparatus of claim 1, wherein the injectionlevel information corresponds to a value at least 3 dB larger than arequired SNR value corresponding to the core layer signal before thecombining.
 4. The apparatus of claim 1, wherein the Physical Layer Pipesare multiplexed by Frequency Division Multiplexing (FDM), and signalinginformation corresponding to the Frequency Division Multiplexing issignaled only for core layer physical layer pipes and is not signaledfor enhanced layer physical layer pipes.
 5. The apparatus of claim 4,wherein the signaling information corresponding to the FrequencyDivision Multiplexing includes at least one of physical layer pipe typeinformation (L1D_plp_type), physical layer pipe subslice intervalinformation (L1D_plp_subslice_interval) and physical layer pipe subslicenumber information (L1D_plp_num_subslices).
 6. The apparatus of claim 5,wherein the enhanced layer physical layer pipe follows a cell writingorder corresponding to the signaling information corresponding to theFrequency Division Multiplexing of the core layer physical layer pipe towhich the enhanced layer physical layer pipe is layered divisionmultiplexed when the Frequency Division Multiplexing is performed. 7.The apparatus of claim 6, the enhanced layer physical layer pipes whichare Frequency Division Multiplexed have a total size not exceeding 2²⁰cells.
 8. The apparatus of claim 1, wherein the Physical Layer Pipesincludes two or more core layer physical layer pipes and a timeinterleaving mode corresponding to the time interleaver is one of hybridtime interleaving mode or no time interleaving mode when the enhancedlayer physical layer pipe is layered division multiplexed to the two ormore core layer physical layer pipes.
 9. The apparatus of claim 8,wherein the two or more core layer physical layer pipes have integernumbers of FEC blocks when the no time interleaving mode is used. 10.The apparatus of claim 8, wherein the two or more core layer physicallayer pipes have the same time interleaving block size or timeinterleaving block sizes, differences between the time interleavingblock sizes being less than a predetermined value, when the hybrid timeinterleaving mode is used.
 11. The apparatus of claim 1, wherein thePhysical Layer Pipes have the start position information and the sizeinformation which are set not to have any duration where the layereddivision multiplexing is not applied in the core layer physical layerpipe which is layered division multiplexed with the enhanced layerphysical layer pipe.
 12. The apparatus of claim 1, wherein the corelayer physical layer pipe is modulated by any one of QPSK, 16 QAM and 64QAM, and is encoded by a code rate of up to 7/15 when the 64 QAM isused.
 13. The apparatus of claim 1, wherein the Physical Layer Pipes forone complete delivered product are up to four physical layer pipes. 14.A method of generating broadcast signal frame, comprising: generating amultiplexed signal by combining a core layer signal and an enhancedlayer signal; reducing power of the multiplexed signal to a power levelcorresponding to the core layer signal; generating a time-interleavedsignal by performing time-interleaving that is applied to both the corelayer signal and the enhanced layer signal; and generating a broadcastsignal frame including a preamble for signaling start positioninformation and the size information for each of Physical Layer Pipes(PLPs), wherein the Physical Layer Pipes include a core layer physicallayer pipe corresponding to the core layer signal and an enhanced layerphysical layer pipe corresponding to the enhanced layer signal, andinjection level information corresponding to the enhanced layer signalis signaled corresponding to the enhanced layer physical layer pipe. 15.The method of claim 14, wherein the Physical Layer Pipes includes two ormore enhanced layer physical layer pipes and the two or more enhancedlayer physical layer pipes have the same injection level informationwhen the core layer physical layer pipe is layered division multiplexedwith the two or more enhanced layer physical layer pipes.